Exhibit 32.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002



In connection with the Quarterly Report of Calpine Corporation (the "Company")
on Form 10-Q for the period ending June 30, 2005, as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), each of the
undersigned does hereby certify, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that, to the best of
his knowledge, based upon a review of the Report:

(1) The Report fully complies with the requirements of Section 13(a) or 15(d) of
the Securities Exchange Act of 1934; and

(2) The  information  contained in the Report fairly  presents,  in all material
respects, the financial condition and results of operation of the Company.

/s/ PETER CARTWRIGHT                    /s/ ROBERT D. KELLY
- ------------------------------          ------------------------------
Peter Cartwright                        Robert D. Kelly
Chairman, President and                 Executive Vice President and
Chief Executive Officer                 Chief Financial Officer
Calpine Corporation                     Calpine Corporation


Dated: August 9, 2005

A signed  original of this  written  statement  required by Section 906 has been
provided to Calpine  Corporation and will be retained by Calpine Corporation and
furnished to the Securities and Exchange Commission or its staff upon request.