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                                                                   EXHIBIT 4.3.3

                          SECOND SUPPLEMENTAL INDENTURE

                            Dated as of July 31, 2000

                                     Between

                              CALPINE CORPORATION,

                                    AS ISSUER

                                       and

                              THE BANK OF NEW YORK,

                                   AS TRUSTEE

                           Supplementing the Indenture
                            Dated as of July 8, 1997

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     SECOND SUPPLEMENTAL INDENTURE, dated as of July 31, 2000 (the "Second
Supplemental Indenture"), between Calpine Corporation, a Delaware corporation
(the "Company"), and The Bank of New York, as trustee ("the Trustee").

     WHEREAS, the Company executed and delivered the Indenture dated as of July
8, 1997, to the Trustee to provide for the issuance of $275,000,000 of the
Company's 8 3/4% Senior Notes due 2007, as supplemented by the First
Supplemental Indenture dated as of September 10, 1997(the "Indenture");

     WHEREAS, the Holders (as defined in the Indenture) of a majority in
principal amount of such Senior Notes have approved certain amendments proposed
by the Company to certain provisions of the Indenture, and the Company desires
to supplement and amend the Indenture accordingly as contemplated by Section 8.2
thereof;

     WHEREAS, all things necessary to make this Second Supplemental Indenture a
valid agreement of the Company and the Trustee in accordance with its terms and
a valid amendment and supplement to the Indenture, have been done.

     NOW THEREFORE, for and in consideration of the premises and mutual
covenants herein contained, the Company and the Trustee agree as follows:

                                    ARTICLE I
                                   DEFINITIONS

     Section 1.1 Definition of Terms

     Unless the context otherwise requires

     (a)  capitalized terms used herein that are not otherwise defined herein
shall have the meaning assigned to such terms in the Indenture;

     (b)  the singular includes the plural and vice versa;

     (c)  headings are for convenience of reference only and do not affect
interpretation.

                                   ARTICLE II
                           AMENDMENTS TO THE INDENTURE

     Section 2.1 Amendments

     (a)  The following definitions in Section 1.1 of the Indenture are amended
to read in their entirety as follows:

     "Non-Recourse Debt" means Indebtedness of the Company or any Restricted
     Subsidiary that is Incurred to finance the exploration, drilling,


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     development, construction or purchase of or by, or repairs, improvements or
     additions to, property or assets of the Company or any Restricted
     Subsidiary, provided that such Indebtedness is without recourse to the
     Company or any Restricted Subsidiary or to any property or assets of the
     Company or any Restricted Subsidiary other than property or assets
     (including Capital Stock) subject to a Lien permitted pursuant to Section
     3.7 (f) or (p).

     "Subsidiary" means, as applied to any Person, any corporation, limited or
     general partnership, trust, association or other business entity of which
     an aggregate of at least 50% of the outstanding Voting Shares or an
     equivalent controlling interest therein, of such Person is, at the time,
     directly or indirectly, owned by such Person and/or one or more
     Subsidiaries of such Person.

     (b)  Clause (vii) of Section 3.4(b) is amended to read in its entirety:

     Non-Recourse Debt of a Restricted Subsidiary.

     (c)  Section 3.7(f) of the Indenture is amended to read in its entirety:

          (1)  Liens incurred by the Company or any Restricted Subsidiary
     securing Indebtedness Incurred by the Company or such Restricted
     Subsidiary, as the case may be, to finance the exploration, drilling,
     development, construction or purchase of or by, or repairs, improvements or
     additions to, property or assets of the Company or such Restricted
     Subsidiary, as the case may be, which Liens may include Liens on the
     Capital Stock of such Restricted Subsidiary or (2) Liens incurred by any
     Restricted Subsidiary that does not own, directly or indirectly, at the
     time of such original incurrence of such a Lien under this clause (2) any
     operating properties or assets, securing Indebtedness Incurred to finance
     the exploration, drilling, development, construction or purchase of or by,
     or repairs, improvements or additions to, property or assets of any
     Restricted Subsidiary that does not, directly or indirectly, own any
     operating properties or assets at the time of such original incurrence of
     such Lien, which Liens may include Liens on the Capital Stock of one or
     more Restricted Subsidiaries that do not, directly or indirectly, own any
     operating properties or assets at the time of such original incurrence of
     such Lien, provided, however, that the Indebtedness secured by any such
     Lien may not be issued more than 365 days after the later of the
     exploration, drilling, development, completion of construction, purchase,
     repair, improvement, addition or commencement of full commercial operation
     of the property or asset being so financed;

     (d)  Section 3.7(l) is deleted in its entirety and the term "[Deleted]" is
inserted in lieu thereof.


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     (e)  Section 3.7(p) is amended to read in its entirety:

     Liens to secure any refinancing, refunding, extension, renewal or
     replacement (or successive refinancings, refundings, extensions, renewals
     or replacements) as a whole, or in part, of any Indebtedness secured by any
     Lien referred to in the foregoing clauses (f), (g), (h) and (i), provided,
     however, that (x) such new Lien shall be limited to all or part of the same
     property or assets that secured the original Lien (plus repairs,
     improvements or additions to such property or assets and Liens on the stock
     or other ownership interest in one or more Restricted Subsidiaries
     beneficially owning such property or assets) and (y) the amount of the
     Indebtedness secured by such Lien at such time (or, if the amount that may
     be realized in respect of such Lien is limited, by contract or otherwise,
     such limited lesser amount) is not increased (other than by an amount
     necessary to pay fees and expenses, including premiums, related to the
     refinancing, refunding, extension, renewal or replacement of such
     Indebtedness);

                                   ARTICLE III
                                  MISCELLANEOUS

     Section 3.1 Notification to Holders.

     The Company shall notify the Holders in accordance with Section 8.2 of the
Indenture of the execution of this Second Supplemental Indenture.

     Section 3.2 Ratification of Indenture.

     The Indenture, as supplemented by this Second Supplemental Indenture, is in
all respects ratified and confirmed, and this Second Supplemental Indenture
shall be deemed part of the Indenture in the manner and to the extent herein and
therein provided.

     Section 3.3 Governing Law.

     This Second Supplemental Indenture shall be deemed to be a contract made
under the laws of the State of New York, and for all purposes shall be construed
in accordance with the laws of said State.

     Section 3.4 Separability.

     In case any one or more of the provisions contained in this Second
Supplemental Indenture shall for any reason be held to be invalid, illegal or
unenforceable in any respect, such invalidity, illegality or unenforceability
shall not affect any other provisions of this Second Supplemental Indenture but
this Second Supplemental Indenture shall be construed as if such invalid or
illegal or unenforceable provision had never been contained herein or therein.


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     Section 3.5 Counterparts.

     This Second Supplemental Indenture may be executed in any number of
counterparts each of which shall be an original; but such counterparts shall
together constitute but one and the same instrument.

     Section 3.6 Effectiveness.

     This Second Supplemental Indenture shall be effective and binding when
executed by the Company and the Trustee.

     Section 3.7 Trustee Not Responsible for Recitals.

     The recitals herein contained are made by the Company and not by the
Trustee, and the Trustee assumes no responsibility for the correctness thereof.
The Trustee makes no representation as to the validity or sufficiency of this
Second Supplemental Indenture.

     Section 3.8 Performance by Trustee.

     The Trustee, for itself and its successors accepts the Trust of the
Indenture as amended by this Second Supplemental Indenture and agrees to perform
the same, but only upon the terms and conditions set forth in the Indenture,
including the terms and provisions defining and limiting the liability and
responsibility of the Trustee.

                                      * * *


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     IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental
Indenture to be duly executed as of the day and year first above written.

                                        CALPINE CORPORATION


                                        By: /s/ ANN B. CURTIS
                                           -------------------------------------
                                           Ann B. Curtis
                                           Executive Vice President and
                                           Chief Financial Officer



                                        THE BANK OF NEW YORK
                                        as Trustee

                                        By: /s/ MICHELE L. RUSSO
                                           -------------------------------------
                                           Name: Michele L. Russo
                                           Title: Assistant Vice President



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