UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K/A

AMENDMENT NO.1

TO ANNUAL REPORT PURSUANT TO SECTIONS 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

(Mark One)

For the fiscal year ended December 31, 2015

OR

For the transition period from                      to                     

Commission File Number 0-21074

SUPERCONDUCTOR TECHNOLOGIES INC.

(Exact name of registrant as specified in its charter)

9101 Wall Street, Suite 1300, Austin, Texas 78754

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (512) 334-8900

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act:

None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ¨    or    No  x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    Yes  ¨    or    No  x

Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x    or    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  x    or    No  ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of Registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definition of “large accelerated filer,” “accelerated filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes    ¨    or    No  x

The aggregate market value of the common stock held by non-affiliates was $15.4 million as of June 27, 2015. The closing price of the common stock on that date was $1.05 as reported by the NASDAQ Capital Market. For purposes of this determination, we excluded the shares of common stock held by each officer and director and by each person who was known to us to own 10% or more of the outstanding common stock as of June 27, 2015. The exclusion of shares owned by the aforementioned individuals and entities from this calculation does not constitute an admission by any of such individuals or entities that he or it was or is an affiliate of ours.

We had 40,748,218 shares of common stock outstanding as of the close of business on March 15, 2016.

EXPLANATORY NOTE

This Amendment No. 1 to Form 10-K (this “Amendment”) of Superconductor Technologies Inc. (the “Company”) amends our Annual Report on Form 10-K for the fiscal year ended December 31, 2015 originally filed with the Securities and Exchange Commission (the “SEC”) on March 30, 2016 (the “Original Filing”). This Amendment is being filed for the purpose of correcting clerical errors in the Exhibit List contained in the Original Filing and in Exhibit 23 – Consent of Independent Registered Public Accounting Firm filed with the Original Filing. No other information included in the Original Filing has been amended. Except for the matter described above, this amendment does not change any previously reported financial results, modify or update disclosures in the Original Filing, or reflect events occurring after the date of the filing of the Original Filing.

As required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended, this Amendment includes new certifications by our principal executive officer and principal financial officer under Section 302 of the Sarbanes-Oxley Act of 2002 in addition to those filed with the Original Filing. We are not including new certifications under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment.

PART IV

(a) The following documents are filed as part of this Report:

1. Index to Financial Statements. Our consolidated financial statements and the Report of Marcum LLP, Independent Registered Public Accounting Firm are included in Part IV of this Report on the pages indicated:

2. Financial Statement Schedule Covered by the Foregoing Report of Independent Registered Public Accounting Firm.

All other schedules are omitted because they are not applicable or the required information is shown in the financial statements or the notes thereto.

3. Exhibits

(b) Exhibits. See Item 15(a) above.

SIGNATURES

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized, on this 22nd day of July 2016.