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                          SIXTH SUPPLEMENTAL INDENTURE

                  SIXTH SUPPLEMENTAL INDENTURE, dated as of July 26, 2002 (the
"Supplemental Indenture") between PECOM ENERGIA S.A., a sociedad anonima duly
organized and existing under the laws of Argentina (the "Company"), and
CITIBANK, N.A., a national banking association incorporated and existing under
the laws of the United States of America, as Trustee (the "Trustee"). All
capitalized terms used herein but not defined herein shall have the meanings
given in the Indenture, unless otherwise indicated.

                  WHEREAS, the Company and the Trustee are parties to that
certain Indenture dated as of May 1, 1998 (the "Indenture") pursuant to which
the Company issued its 9% Series B Notes due 2006 (the "Series B Notes");

                  WHEREAS, pursuant to Section 902 of the Indenture, the
Company, when authorized by a Corporate Resolution, and the Trustee, with the
consent or vote of the Holders of not less than a majority in aggregate
principal amount of the Outstanding Securities thereby affected, may amend or
supplement certain provisions of the Indenture;

                  WHEREAS, the Company desires to amend the Indenture to delete
certain covenants and other provisions contained therein with respect to the
Series B Notes;

                  WHEREAS, pursuant to an offering memorandum and a pricing
supplement each dated June 10, 2002 (the "Offer"), the Company offered to
exchange all of the Company's outstanding Series B Notes for its 9% Notes due
2009 (the "New Notes"), and solicited proxies to the amendments to the Indenture
described therein;

                  WHEREAS, Holders of at least a majority in principal amount of
the outstanding Series B Notes have approved a Corporate Resolution at a duly
convened noteholders meeting (the "Meeting") which authorizes the Company to so
amend the Indenture;

                  WHEREAS, the CNV confirmed that the Meeting conformed with its
legal requirements; and

                  WHEREAS, by entering into this Supplemental Indenture, the
Company and the Trustee have consented to amend the Indenture in accordance with
the terms and conditions herein.

                  NOW, THEREFORE, in consideration of the foregoing and for
other good and valuable consideration, the receipt of which is hereby
acknowledged by the Company and the Trustee hereby agree for the benefit of each
other and the equal and ratable benefit of the Holders of the Series B Notes as
follows:

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                                    ARTICLE I

                                   AMENDMENTS

         Section 1.01. Amendments to the Indenture. On the Operative Date (as
hereinafter defined) the Indenture is amended as set forth herein.

                  (a)      Section 501 of the Indenture is hereby amended by
         deleting paragraphs (3) through (12), each in its entirety and
         inserting in lieu of each such paragraph "[Intentionally Deleted.]",
         and by deleting the definition of "Bankruptcy Law" appearing at the end
         of Section 501.

                  (b)      Section 801 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (c)      Section 1004 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (d)      Section 1005 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (e)      Section 1006 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (f)      Section 1007 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (g)      Section 1009 of the Indenture is hereby amended by
         deleting it in its entirety and inserting in lieu thereof
         "[Intentionally Deleted.]".

                  (h)      Section 101 of the Indenture is hereby amended by
         deleting those definitions which appear solely in the text deleted from
         the Indenture pursuant to the amendments contained herein.

                                   ARTICLE II

                     CONDITION PRECEDENT AND OPERATIVE DATE

         Section 2.01. Compliance with and Fulfillment of Conditions Precedent.
The Company has complied with all conditions precedent provided in the Indenture
and this Supplemental Indenture to the execution and delivery of this
Supplemental Indenture (along with such documentation relating thereto as the
Trustee shall require, including, without limitation, an Opinion of Counsel as
to the enforceability of the Supplemental Indenture and an Officers'
Certificate).

         Section 2.02. Operative Date. This Supplemental Indenture shall become
operative on the date (the "Operative Date") on which Pecom Energia S.A. accepts
all Series B Notes validly

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tendered and not withdrawn pursuant to the Offer and has irrevocably delivered
to the Exchange Agent the New Notes for delivery to the holders thereof.

                                   ARTICLE III

                                  MISCELLANEOUS

         Section 3.01. Relation to Existing Indenture. This Supplemental
Indenture constitutes an integral part of the Indenture (the provisions of
which, as modified by the Supplemental Indenture, shall apply to the Series B
Notes) in respect of the Series B Notes but shall not modify, amend or otherwise
affect the Indenture insofar as it relates to any other Series of Securities or
affect in any manner the terms or conditions of the Securities of any other
Series.

         Section 3.02. Construction. For all purposes of this Supplemental
Indenture, except as otherwise herein expressly provided or unless the context
otherwise requires: (i) the terms and expressions used herein shall have the
same meanings as corresponding terms and expressions used in the Indenture; and
(ii) the words "herein," "hereof" and "hereby" and other words of similar import
used in this Supplemental Indenture refer to this Supplemental Indenture as a
whole and not to any particular Section hereof.

         Section 3.03. Trustee Acceptance. The Trustee accepts the amendment of
the Indenture effected by this Supplemental Indenture, as hereby amended, but
only upon the terms and conditions set forth in the Indenture, as hereby
amended, including the terms and provisions defining and limiting the
liabilities and responsibilities of the Trustee in the performance of its duties
and obligations under the Indenture, as hereby amended. Without limiting the
generality of the foregoing, the Trustee has no responsibility for the
correctness of the recitals of fact herein contained which shall be taken as the
statements of the Company, and makes no representations as to the validity or
enforceability against the Company.

         Section 3.04. Indenture Ratified. Except as expressly amended hereby,
the Indenture is in all respects ratified and confirmed and all the terms,
conditions and provisions thereof shall remain in full force and effect.

         Section 3.05. Parties Bound. This Supplemental Indenture shall form a
part of the Indenture for all purposes, and every holder of the Series B Notes
heretofore or hereafter authenticated and delivered shall be bound hereby. Upon
the execution of this Supplemental Indenture, the Indenture and the Series B
Notes theretofore issued shall be deemed to be modified and amended in
accordance with this Supplemental Indenture and the respective rights,
limitation of rights, obligations, duties and immunities under the Indenture of
the Company and the Trustee and the Holders of the Series B Notes shall
thereafter be determined, exercised and enforced thereunder subject in all
respects to such modifications and amendments, and all the terms and conditions
of this Supplemental Indenture shall be and be deemed to be part of the terms
and conditions of the Indenture and the Series B Notes theretofore issued for
any and all purposes.

         Section 3.06. Successors and Assignees. This Supplemental Indenture
shall be binding upon and inure to the benefit of the parties hereto and their
respective successors and assigns.

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         Section 3.07. Counterparts. This Supplemental Indenture may be executed
in any number of counterparts, each of which when so executed shall be deemed to
be an original, and all of such counterparts shall together constitute one and
the same instrument.

         Section 3.08. Severability. In case any provision in this Supplemental
Indenture shall be invalid, illegal or unenforceable, the validity, legality and
enforceability of the remaining provisions shall not in any way be affected or
impaired thereby.

         Section 3.09. Headings. The headings of the Articles and Sections of
this Supplemental Indenture have been inserted for convenience of reference only
and are not to be considered part of this Supplemental Indenture and shall in no
way modify or restrict any of the terms or provisions hereof.

         Section 3.10. Governing Law. This Supplemental Indenture shall be
governed by and construed in accordance with the internal laws of the State of
New York without giving effect to principles of conflicts of laws.

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

                                              PECOM ENERGIA S.A.

                                              By:_______________________________
                                                 Name:
                                                 Title:

                                              By:_______________________________
                                                 Name:
                                                 Title:

                                              CITIBANK, N.A., as Trustee

                                              By:_______________________________
                                                 Name:
                                                 Title:

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