UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 10-Q

(Mark One)

[X]

QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2005

OR

[  ]

TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from           to           

Commission File Number 1-7176

El Paso CGP Company

(Exact Name of Registrant as Specified in its Charter)

Telephone Number: (713) 420-2600

Internet Website: www.elpaso.com

     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 þ No o

     Indicate by check mark whether the registrant is an accelerated filer (as defined in Rule 12b-2 of the Exchange Act).  Yes o No þ

     Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date.

      Common Stock, par value $1 per share. Shares outstanding on May 12, 2005: 1,000

      EL PASO CGP COMPANY MEETS THE CONDITIONS OF GENERAL INSTRUCTION H(1)(a) AND (b) OF FORM 10-Q AND IS THEREFORE FILING THIS REPORT WITH A REDUCED DISCLOSURE FORMAT AS PERMITTED BY SUCH INSTRUCTION.

EL PASO CGP COMPANY

TABLE OF CONTENTS

     Below is a list of terms that are common to our industry and used throughout this document:

     When we refer to natural gas and oil in “equivalents,” we are doing so to compare quantities of oil with quantities of natural gas or to express these different commodities in a common unit. In calculating equivalents, we use a generally recognized standard in which one Bbl of oil is equal to six Mcf of natural gas. Also, when we refer to cubic feet measurements, all measurements are at a pressure of 14.73 pounds per square inch.

     When we refer to “us”, “we”, “our”, “ours”, or “El Paso CGP”, we are describing El Paso CGP Company and/or our subsidiaries.

PART I — FINANCIAL INFORMATION

Item 1. Financial Statements

EL PASO CGP COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(In millions)

(Unaudited)

See accompanying notes.

EL PASO CGP COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS

(In millions, except share amounts)

(Unaudited)

See accompanying notes.

EL PASO CGP COMPANY

CONDENSED CONSOLIDATED BALANCE SHEETS — (Continued)

(In millions, except share amounts)

(Unaudited)

See accompanying notes.

EL PASO CGP COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(In millions)

(Unaudited)

See accompanying notes.

EL PASO CGP COMPANY

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(In millions)

(Unaudited)

See accompanying notes.

EL PASO CGP COMPANY

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

1. Basis of Presentation and Significant Accounting Policies

     Basis of Presentation

      We are a wholly-owned, direct subsidiary of El Paso Corporation (El Paso). We prepared this Quarterly Report on Form 10-Q under the rules and regulations of the United States Securities and Exchange Commission. Because this is an interim period filing presented using a condensed format, it does not include all of the disclosures required by generally accepted accounting principles. You should read this Quarterly Report on Form 10-Q along with our 2004 Annual Report on Form 10-K, which includes a summary of our significant accounting policies and other disclosures. The financial statements as of March 31, 2005, and for the quarters ended March 31, 2005 and 2004, are unaudited. We derived the balance sheet as of December 31, 2004, from the audited balance sheet filed in our 2004 Annual Report on Form 10-K. In our opinion, we have made all adjustments which are of a normal, recurring nature to fairly present our interim period results. Due to the seasonal nature of our businesses, information for interim periods may not be indicative of the results of operations for the entire year. In mid-2004, we discontinued our Canadian and certain other international natural gas and oil production operations. Our results for all periods reflect these operations as discontinued.

     Significant Accounting Policies

      Our significant accounting policies are consistent with those discussed in our 2004 Annual Report on Form 10-K.

     New Accounting Pronouncements Issued But Not Yet Adopted

      As of March 31, 2005, there were several accounting standards and interpretations that had not yet been adopted by us. Below is a discussion of significant standards that may impact us.

      Accounting for Deferred Taxes on Foreign Earnings. In December 2004, the Financial Accounting Standards Board (FASB) issued FASB Staff Position (FSP) No. 109-2, Accounting and Disclosure Guidance for the Foreign Earnings Repatriation Provision within the American Jobs Creation Act of 2004. FSP No. 109-2 clarified the existing accounting literature that requires companies to record deferred taxes on foreign earnings, unless they intend to indefinitely reinvest those earnings outside the United States. This pronouncement will temporarily allow companies that are evaluating whether to repatriate foreign earnings under the American Jobs Creation Act of 2004 to delay recognizing any related taxes until that decision is made. This pronouncement also requires companies that are considering repatriating earnings to disclose the status of their evaluation and the potential amounts being considered for repatriation. The United States Treasury Department has not issued final guidelines for applying the repatriation provisions of the American Jobs Creation Act. We have not yet determined the potential range of our foreign earnings that could be impacted by this legislation and FSP No. 109-2, and we continue to evaluate whether we will repatriate any foreign earnings and the impact, if any, that this pronouncement will have on our financial statements.

      Accounting for Asset Retirement Obligations. In March 2005, the FASB Issued FASB Interpretation (FIN) No. 47, Accounting for Conditional Asset Retirement Obligations. FIN No. 47 requires companies to record a liability for those asset retirement obligations in which the timing or amount of settlement of the obligations are uncertain. These conditional obligations were not addressed by Statement of Financial Accounting Standards (SFAS) No. 143, which we adopted on January 1, 2003. FIN No. 47 will require us to accrue a liability only when a range of scenarios indicate that the potential timing and settlement amounts of our conditional asset retirement obligations can be determined. We will adopt the provisions of this standard in the fourth quarter of 2005 and have not yet determined the impact, if any, that this pronouncement will have on our financial statements.

2. Divestitures

      During the quarters ended March 31, 2005 and 2004, we completed the sale of a number of assets and investments. Our Power segment received cash proceeds from asset and investment sales of $3 million in each of the quarters ended March 31, 2005 and 2004. Additionally, in the quarters ended March 31, 2005 and 2004, we received proceeds of $79 million and $1,243 million from sales of assets related to our discontinued operations.

      The following table summarizes the significant assets sold during the quarters ended March 31:

      In April 2005, we also completed the sale of a power turbine for $15 million.

      Under SFAS No. 144, Accounting for the Impairment or Disposal of Long-Lived Assets, we classify assets to be disposed of as held for sale or, if appropriate, discontinued operations when they have received appropriate approvals by El Paso’s management or its Board of Directors and when they meet other criteria. As of March 31, 2005 and December 31, 2004, we had assets held for sale related to certain domestic power assets, which were fully impaired in previous years and which we expect to sell within the next twelve months.

      International Natural Gas and Oil Production Operations. During 2004, our Canadian and certain other international natural gas and oil production operations were approved for sale. As of December 31, 2004, we had completed the sale of all of our Canadian operations and substantially all of our operations in Indonesia for total proceeds of approximately $389 million. We expect to complete the sale of the remainder of these properties in 2005.

      Petroleum Markets. During 2003, El Paso’s Board of Directors approved the sales of our petroleum markets businesses and operations. These businesses and operations consisted of our Eagle Point and Aruba refineries, our asphalt business, our Florida terminal, tug and barge business, our lease crude operations, our Unilube blending operations, our domestic and international terminalling facilities and our petrochemical and chemical plants. In 2004, we completed the sales of our Aruba and Eagle Point refineries for approximately $880 million.

      The petroleum markets and other international natural gas and oil production operations discussed above are classified as discontinued operations in our financial statements. All of the assets and liabilities of these discontinued businesses are classified as current assets and liabilities as of March 31, 2005 and December 31, 2004. The summarized operating results data and financial position data of our discontinued operations were as follows: