Exhibit 99.4

INTERNATIONAL ISOTOPES INC.

REGISTRATION RIGHTS AGREEMENT

REGISTRATION RIGHTS AGREEMENT, dated as of July 27, 2012, between INTERNATIONAL ISOTOPES INC., a Texas corporation (the “Company”) and each purchaser identified on Schedule A hereto (each, including their respective successors and assigns, an “Investor” and collectively, the “Investors”).  Capitalized terms used, but not otherwise defined, in this Agreement have the meanings ascribed to such terms in the Securities Purchase Agreement, dated on or about the date hereof (the “Securities Purchase Agreement”, among the parties hereto and Euro Pacific Capital as the Placement Agent and Investor Representative.

NOW, THEREFORE, in consideration of the foregoing and other good and valuable consideration, the parties hereto agree as follows:

1.

Piggyback Registration.

(a)  The Company shall give the Investors at least 10 days’ prior written notice of each filing by the Company of a registration statement (other than a registration statement on Form S-4 or Form S-8 or on any successor forms thereto) with the Securities Exchange Commission (the “Commission”) pursuant to which the Company is registering shares of its Common Stock for sale by itself or others for cash proceeds. If requested by the Investors or the Investor Representative in writing within 20 days after receipt of any such notice, the Company shall, at the Company’s sole expense (other than the underwriting discounts, if any, payable in respect of the Shares sold by the Investors), register all or, at the Investors’ option, any portion of the shares of common stock issuable upon conversion or exercise of the Securities held by the Investors (the “Shares”), concurrently with the registration of such other securities, all to the extent requisite to permit the public offering and sale of the Shares through the securities exchange, if any, on which the Common Stock is being sold or on the over-the-counter market, and will use its commercially reasonable efforts through its officers, directors, auditors, and counsel to cause such registration statement to become effective as promptly as practicable. If the managing underwriter of any such offering shall determine and advise the Company that, in its opinion, the distribution of all or a portion of the Shares requested to be included in the registration concurrently with the securities being registered by the Company would adversely affect the distribution of such securities by the Company, then the Company will include in such registration first, the securities that the Company proposes to sell itself and second, the Shares requested to be included in such registration, to the extent permitted by the managing underwriter.

(b) In the event of a registration pursuant to the provisions of this Agreement, the Company shall use its reasonable commercial efforts to cause the Shares so registered to be registered or qualified for sale under the securities or blue sky laws of such jurisdictions as the Investors may reasonably request, if such registration or qualification is required; provided, however, that the Company shall not be required to qualify to do business in any state by reason of this Section 1(b) in which it is not otherwise required to qualify to do business.

(c) In the event of a registration pursuant to the provisions of this Agreement, the Company shall furnish to the Investors such reasonable number of copies of the registration statement and of each amendment and supplement thereto (in each case, including all exhibits), of each prospectus contained in such registration statement and each supplement or amendment thereto (including each preliminary prospectus), all of which shall conform to the requirements of the Securities Act and the rules and regulations thereunder, and such other documents, as the Investors may reasonably request to facilitate the disposition of the Shares included in such registration.

(d) The Company shall notify the Investors promptly when such registration statement has become effective or a supplement to any prospectus forming a part of such registration statement has been filed.

(e) The Company shall advise the Investors promptly after it shall receive notice or obtain knowledge of the issuance of any stop order by the Commission suspending the effectiveness of such registration statement, or the initiation or threatening of any proceeding for that purpose and promptly use its reasonable best efforts to prevent the issuance of any stop order or to obtain its withdrawal if such stop order should be issued.

(f) The Company shall promptly notify the Investors at any time when a prospectus relating thereto is required to be delivered under the Securities Act of the happening of any event as a result of which the prospectus included in such registration statement, as then in effect, would include an untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances then existing, and at the reasonable request of the Investors prepare and furnish to it such number of copies of a supplement to or an amendment of such prospectus as may be necessary so that, as thereafter delivered to the purchasers of such Shares or securities, such prospectus shall not include an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading in the light of the circumstances under which they were made. The Investors shall suspend all sales of the Shares upon receipt of such notice from the Company and shall not re-commence sales until it receives copies of any necessary amendment or supplement to such prospectus, which shall be delivered to the Investors within 30 days of the date of such notice from the Company.

(g) If requested by the underwriter for any underwritten offering of Shares, the Company and the Investors will enter into an underwriting agreement with such underwriter for such offering, which shall be reasonably satisfactory in substance and form to the Company, the Company’s counsel and the Investors’ counsel, and the underwriter, and such agreement shall contain such representations and warranties by the Company and the Investors and such other terms and provisions as are customarily contained in an underwriting agreement with respect to secondary distributions solely by selling stockholders, including, without limitation, indemnities substantially to the effect and to the extent provided in Section 2 of this Agreement.  If the Investors do not enter into such underwriting agreement, the Company shall have no obligation to include the Investors’ Shares in the registration statement relating to such offering.

(h) The Company agrees that until all the Shares have been sold under a registration statement or pursuant to Rule 144 promulgated under the Securities Act or other available exemption from Securities Act registration requirements, it shall use its reasonable commercial efforts to keep current in filing all reports, statements and other materials required to be filed with the Commission to permit the Investors to sell the Shares under Rule 144.

2.

Indemnification.

(a) Subject to the conditions set forth below, the Company agrees to indemnify and hold harmless the Investors, their employees, agents, and counsel, and each person, if any, who controls any such person within the meaning of Section 15 of the Securities Act or Section 20(a) of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”) from and against any and all loss, liability, charge, claim, damage, and expense whatsoever (which shall include, for all purposes of this Section 2, but not be limited to, attorneys’ fees and any and all reasonable expenses whatsoever incurred in investigating, preparing, or defending against any litigation, commenced or threatened, or any claim whatsoever, and any and all amounts paid in settlement of any claim or litigation) as and when incurred, arising out of, based upon, or in connection with (i) any untrue statement or alleged untrue statement of a material fact contained (A) in any registration statement, preliminary prospectus, or final prospectus (as from time to time amended and supplemented) or any amendment or supplement thereto, relating to the sale of any of the Shares or (B) in any application or other document or communication (in this Section 2 collectively called an “application”) executed by or on behalf of the Company or based upon written information furnished by or on behalf of the Company filed in any jurisdiction in order to register or qualify any of the Shares under the securities or blue sky laws thereof or filed with the Commission or any securities exchange; or any omission or alleged omission to state a material fact required to be stated therein or necessary to make the statements made therein not misleading, unless (x) such statement or omission was made in reliance upon and in conformity with written information furnished to the Company with respect to the Investors by or on behalf of the Investors expressly for inclusion in any registration statement, preliminary prospectus, or final prospectus, or any amendment or supplement thereto, or in any application, as the case may be, or (y) such loss, liability, charge, claim, damage or expense arises out of the Investors’ failure to comply with the terms and provisions of this Agreement, or (ii) any breach of any representation, warranty, covenant, or agreement of the Company contained in this Agreement. The foregoing agreement to indemnify shall be in addition to any liability the Company may otherwise have, including liabilities arising under this Agreement.

If any action is brought against the Investors or any of their employees, agents, or counsel, or any controlling persons of such person (an “indemnified party”) in respect of which indemnity may be sought against the Company pursuant to the foregoing paragraph, such indemnified party or parties shall promptly notify the Company in writing of the institution of such action (but the failure so to notify shall not relieve the Company from any liability other than pursuant to this Section 2(a)) and the Company shall promptly assume the defense of such action, including the employment of counsel provided that the indemnified party shall have the right to employ its or their own counsel in any such case, but the fees and expenses of such counsel shall be at the expense of such indemnified party or parties unless the employment of such counsel shall have been authorized in writing by the Company in connection with the defense of such action or the Company shall not have promptly employed counsel reasonably satisfactory to such indemnified party or parties to have charge of the defense of such action or such indemnified party or parties shall have reasonably concluded that there may be one or more legal defenses available to it or them or to other indemnified parties which are different from or additional to those available to the Company, in any of which events such fees and expenses shall be borne by the Company and the Company shall not have the right to direct the defense of such action on behalf of the indemnified party or parties. Anything in this Section 2 to the contrary not withstanding, the Company shall not be liable for any settlement of any such claim or action effected without its written consent, which shall not be unreasonably withheld. The Company shall not, without the prior written consent of each indemnified party that is not released as described in this sentence, settle or compromise any action, or permit a default or consent to the entry of judgment in or otherwise seek to terminate any pending or threatened action, in respect of which indemnity may be sought hereunder (whether or not any indemnified party is a party thereto) unless such settlement, compromise, consent, or termination includes an unconditional release of each indemnified party from all liability in respect of such action. The Company agrees promptly to notify the Investors of the commencement of any litigation or proceedings against the Company or any of its officers or directors in connection with the sale of any Shares or any preliminary prospectus, prospectus, registration statement, or amendment or supplement thereto, or any application relating to any sale of any Shares.

(b) The Investors agrees to indemnify and hold harmless the Company, each director of the Company, each officer of the Company who shall have signed any registration statement covering Shares held by the Investors, each other person, if any, who controls the Company within the meaning of Section 15 of the Securities Act or Section 20(a) of the Exchange Act, and its or their respective counsel, to the same extent as the foregoing indemnity from the Company to the Investors in Section 2(a) but only with respect to statements or omissions, if any, made in any registration statement, preliminary prospectus, or final prospectus (as from time to time amended and supplemented) or any amendment or supplement thereto, or in any application, in reliance upon and in conformity with written information furnished to the Company with respect to the Investors by or on behalf of the Investors, expressly for inclusion in any such registration statement, preliminary prospectus, or final prospectus, or any amendment or supplement thereto, or in any application, as the case may be. If any action shall be brought against the Company or any other person so indemnified based on any such registration statement, preliminary prospectus, or final prospectus, or any amendment or supplement thereto, or in any application, and in respect of which indemnity may be sought against the Investors pursuant to this Section 2(b), the Investors shall have the rights and duties given to the Company, and the Company and each other person so indemnified shall have the rights and duties given to the indemnified parties, by the provisions of Section 2(a).

(c) To provide for just and equitable contribution, if (i) an indemnified party makes a claim for indemnification pursuant to Section 2(a) or 2(b) (subject to the limitations thereof) but it is found in a final judicial determination, not subject to further appeal, that such indemnification may not be enforced in such case, even though this Agreement expressly provides for indemnification in such case, or (ii) any indemnified or indemnifying party seeks contribution under the Securities Act, the Exchange Act or other wise, then the Company (including for this purpose any contribution made by or on behalf of any director of the Company, any officer of the Company who signed any such registration statement, any controlling person of the Company, and its or their respective counsel) as one entity, and the Investors (including for this purpose any contribution by or on behalf of an indemnified party) as a second entity, shall contribute to the losses, liabilities, claims, damages, and expenses whatsoever to which any of them may be subject, on the basis of relevant equitable considerations such as the relative fault of the Company and the Investors in connection with the facts which resulted in such losses, liabilities, claims, damages, and expenses. The relative fault, in the case of an untrue statement, alleged untrue statement, omission, or alleged omission shall be determined by, among other things, whether such statement, alleged statement, omission or alleged omission relates to information supplied by the Company or by the Investors, and the parties’ relative intent, knowledge, access to information, and opportunity to correct or prevent such statement, alleged statement, omission, or alleged omission. The Company and the Investors agree that it would be unjust and inequitable if the respective obligations of the Company and the Investors for contribution were determined by pro rata or per capita allocation of the aggregate losses, liabilities, claims, damages, and expenses (even if the Investors and the other indemnified parties were treated as one entity for such purpose) or by any other method of allocation that does not reflect the equitable considerations referred to in this Section 2(c). No person guilty of a fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any person who is not guilty of such fraudulent misrepresentation. For purposes of this Section 2(c) each person, if any, who controls the Investors within the meaning of Section 15 of the Securities Act or Section 20(a) of the Exchange Act and each employee, agent, and counsel of the Investors or control person shall have the same rights to contribution as the Investors and each person, if any, who controls the Company within the meaning of Section 15 of the Securities Act or Section 20(a) of the Exchange Act, each officer of the Company who shall have signed any such registration statement, each director of the Company, and its or their respective counsel shall have the same rights to contribution as the Company, subject to each case to the provisions of this Section 2(c). Anything in this Section 2(c) to the contrary notwithstanding, no party shall be liable for contribution with respect to the settlement of any claim or action effected without its written consent. This Section 2(c) is intended to supersede any right to contribution under the Securities Act, the Exchange Act or otherwise.

3.

Miscellaneous.

(a) Remedies. In the event of a breach by the Company of its obligations under this Agreement, the Investors, in addition to being entitled to exercise all rights granted by law, including recovery of damages, will be entitled to specific performance of their rights under this Agreement.

(b) Agreements and Waivers. The provisions of this Agreement, including the provisions of this sentence, may not be amended, modified or supplemented, unless such amendment, modification or supplement is in writing and signed by the Company and the Investor Representative.

(c) Notices. Any notices, consents, waivers or other communications required or permitted to be given under the terms of this Agreement must be in writing and will be deemed to have been delivered if delivered in accordance with Section 9.2 of the Securities Purchase Agreement.

(d) Successors and Assigns. This Agreement shall inure to the benefit of and be binding upon the successors and assigns of each of the parties.

(e) Counterparts; Facsimile Execution. This Agreement may be executed in any number of counterparts and by the parties hereto in separate counterparts, each of which when so executed shall be deemed to be an original and all of which taken together shall constitute one and the same agreement. Facsimile execution and delivery of this Agreement is legal, valid and binding for all purposes.

(f) Headings. The headings in this Agreement are for convenience of references only and shall not limit or otherwise affect the meaning hereof.

(g)  Governing Law, Consent to Jurisdiction, etc.  All questions concerning the construction, validity, enforcement and interpretation of this Agreement shall be governed by and construed and enforced in accordance with the internal laws of the State of New York, without regard to the principles of conflicts of law thereof (other than Section 5-1401 of the General Obligations Law of the State of New York).  Each party agrees that all legal proceedings concerning the interpretations, enforcement and defense of the transactions contemplated by this Agreement and any other Transaction Documents (whether brought against a party hereto or its respective affiliates, directors, officers, shareholders, employees or agents) shall be commenced exclusively in the state and federal courts sitting in the City of New York.  Each party hereto hereby irrevocably submits to the exclusive jurisdiction of the state and federal courts sitting in the City of New York, New York for the adjudication of any dispute hereunder or in connection herewith or with any transaction contemplated hereby or discussed herein (including with respect to the enforcement of the any of the Transaction Documents), and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding, any claim that it is not personally subject to the jurisdiction of any such court, that such suit, action or proceeding is improper.  Each party hereto hereby irrevocably waives personal service of process and consents to process being served in any such suit, action or proceeding by mailing a copy thereof via registered or certified mail or overnight delivery (with evidence of delivery) to such party at the address in effect for notices to it under this Agreement and agrees that such service shall constitute good and sufficient service of process and notice thereof.  Nothing contained herein shall be deemed to limit in any way any right to serve process in any manner permitted by law.  EACH PARTY HERETO (INCLUDING ITS AFFILIATES, AGENTS, OFFICERS, DIRECTORS AND EMPLOYEES) HEREBY IRREVOCABLY WAIVES, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

(h) Severability. In the event that any one or more of the provisions contained herein, or the application hereof in any circumstance is held invalid, illegal or unenforceable, the validity, legality and enforceability of any such provisions in every other respect and of the remaining provisions contained herein shall not be affected or impaired thereby.

(i) Entire Agreement. This Agreement is intended by the parties as a final expression of their agreement and intended to be a complete and exclusive statement of this agreement and understanding of the parties hereto in respect of the subject matter contained herein. There are no restrictions, promises, warranties or undertakings, other than those set forth or referred to herein, concerning the registration rights granted by the Company pursuant to this Agreement.

(j) Several Obligations.  The obligations of each Investor hereunder are several and not joint with the obligations of any other Investor, and no provision of this Agreement is intended to confer any obligations on any Investor vis-à-vis any other Investor.  Nothing contained herein, and no action taken by any Investor pursuant hereto, shall be deemed to constitute the Investors as a partnership, an association, a joint venture or any other kind of entity, or create a presumption that the Investors are in any way acting in concert or as a group with respect to such obligations or the transactions contemplated herein.

(k)  Rights of the Placement Agent.  The Placement Agent shall have all of the rights of an “Investor” under this Agreement and the Shares issuable upon the exercise of the warrants issued to the Placement Agent (and any capital stock of the Company issued or issuable, with respect to the warrants issued to the Placement Agent as a result of any stock split, stock dividend, recapitalization, exchange, anti-dilution adjustment or similar event or otherwise, without regard to any limitations on exercises of the warrants, if any) constitute Shares for all purposes of this Agreement.  

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IN WITNESS WHEREOF, the parties hereto have caused this Registration Rights Agreement to be duly executed by their respective authorized signatories as of the date first indicated above.

Annex A

Registration Rights Agreement

Investor Counterpart Signature Page

The undersigned, desiring to enter into this Registration Rights Agreement, dated as of _________________, 2012 (the “Agreement”), between the undersigned, International Isotopes Inc., a Texas corporation (the “Company”), and the other parties thereto, in or substantially in the form furnished to the undersigned, hereby agrees to join the Agreement as a party thereto, with all the rights and privileges appertaining thereto, and to be bound in all respects by the terms and conditions thereof.

IN WITNESS WHEREOF, the undersigned has executed the Agreement as of _____________________, 2012.

Schedule A

SCHEDULE OF INVESTORS

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