<PAGE>
                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                       PURSUANT TO SECTION 13 OR 15(d) OF

                       THE SECURITIES EXCHANGE ACT OF 1934

       DATE OF REPORT (DATE OF EARLIEST EVENT REPORTED): JANUARY 31, 2002

                               CALPINE CORPORATION


                            (A DELAWARE CORPORATION)

                        COMMISSION FILE NUMBER: 001-12079

                  I.R.S. EMPLOYER IDENTIFICATION NO. 77-0212977

                           50 WEST SAN FERNANDO STREET

                           SAN JOSE, CALIFORNIA 95113

                            TELEPHONE: (408) 995-5115
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ITEM 5. OTHER EVENTS

On January 31, 2002, Calpine announced financial results for the three and
twelve months ended December 31, 2001. The results reflected the continued
execution of Calpine's strategy to own and operate low-cost generating
facilities in key North American power markets and Calpine Energy Services'
successful risk management and optimization program. However, as a result of the
nationwide economic slowdown, the industry experienced lower industrial demand
during 2001, which, along with unusually mild weather, substantially reduced
prices for power and spark spreads.

ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS

(a) Not applicable.

(b) Not applicable.

(c) Exhibits.

99.0 Press Release dated January 31, 2002
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                                   SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                               CALPINE CORPORATION





                               By:  /s/ Charles B. Clark, Jr.
                                    ------------------------------------
                                    Charles B. Clark, Jr.
                                    Senior Vice President and Controller
                                    Chief Accounting Officer



Date: February 7, 2002
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                                  EXHIBIT INDEX




<TABLE>
<CAPTION>
EXHIBIT NO.      DESCRIPTION
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<S>              <C>
   99.0          Press Release dated January 31, 2002
</TABLE>

