<PAGE>

                                                                 Exhibit 10(g)


                               PURCHASE AGREEMENT


         PURCHASE AGREEMENT ("Agreement") dated as of May 7, 2004, by and among
each of the entities listed on the attached Schedule A (each a "Seller," and
together the "Sellers"), and TXU Corp., a Texas corporation (the "Purchaser").

                                  INTRODUCTION

         Each Seller is a holder of Corporate Units issued by the Purchaser with
a stated amount of $50, consisting of a purchase contract to purchase shares of
the Purchaser's common stock, $25 principal amount of Purchaser's Series K
Senior Notes due November 16, 2006 (the "Series K Notes"), and $25 principal
amount of Purchaser's Series L Senior Notes due November 16, 2007 (the "Series L
Notes"). The Corporate Units are listed on the New York Stock Exchange under the
symbol "TXU Prc" and trade through the book-entry facilities of The Depository
Trust Company ("DTC"). The Corporate Units are referred to in this Agreement as
"Units."

         Each Seller proposes to (i) sell, assign, and transfer its Units to the
Purchaser in accordance with the terms and subject to the conditions set forth
in this Agreement and (ii) settle certain claims as more fully set forth herein.

         The Purchaser proposes to purchase, acquire, and accept each Seller's
Units in accordance with the terms and subject to the conditions set forth in
this Agreement.

         NOW, THEREFORE, in consideration of the premises and agreements
contained herein, the parties hereto agree as follows:

                                   ARTICLE I

                                SALE AND PURCHASE

         SECTION 1.1       Sale and Purchase of Units.

           (a) Subject to the terms and conditions set forth herein, each Seller
hereby severally agrees to sell, assign, transfer, convey and deliver to the
Purchaser, and the Purchaser hereby agrees to purchase, acquire, and accept,
all of each Seller's Units for an aggregate purchase price of $47.75 per Unit,
inclusive of accrued and unpaid interest and contract adjustment payments
thereon (the "Purchase Price"), with each Seller receiving an aggregate Purchase
Price set forth on the attached Schedule A.

           (b) Subject to the terms and conditions of this Agreement, the sale
and purchase of the Units contemplated by this Agreement shall take place in
the manner set forth in this Article I.

           (c) Commencing on May 7, 2004, each Seller shall deliver, or cause to
be delivered, to the securities account designated by the Purchaser and referred
to in the attached Schedule B, security entitlements to the total aggregate
number of Units set forth in respect of such Seller on the attached Schedule A.
Delivery of such security entitlements shall be made in accordance with the
standard operating procedures of DTC's book entry system. Unless the parties
otherwise agree, delivery will be made in accordance with the delivery versus
payment method. In accordance with such method of delivery, Purchaser shall
cause the payment of the Purchase Price in respect of the number of Units so
delivered at any time to be paid to the applicable Seller concurrently with
delivery of such Seller's Units. The "Closing" or "Closings" with respect to the
Sellers' Units shall be deemed to take place, as to the number of Units so
delivered, upon the occurrence of such delivery and payment.
<PAGE>

           (d) Each Seller shall deliver security entitlements as set forth
above in subsection (c) as such securities become available for delivery upon
payment. Deliveries may be made from time-to-time, and at any time prior to the
close of business on May 14, 2004. Deliveries may not be made by a Seller in
excess of the aggregate number of Units set forth in respect of such Seller on
Schedule A.

           (e) Not later than May 14, 2004, the Purchaser shall deliver, or
cause to be delivered, to the respective Sellers, a receipt executed by an
authorized representative evidencing receipt of the aggregate number of Units
sold by such Sellers, and each Seller shall deliver, or cause to be delivered,
to the Purchaser, a receipt executed by an authorized representative evidencing
receipt of the total aggregate Purchase Price for such Seller.

         SECTION 1.2 Assignment of Other Rights. Effective upon the Closing,
each Seller hereby assigns, transfers, conveys and delivers to the Purchaser,
and the Purchaser hereby accepts such assignment, transfer, conveyance and
delivery of, any and all rights that each Seller may have under and in
accordance with the Purchase Contract Agreement dated as of October 1, 2001
between the Purchaser and The Bank of New York, as supplemented and amended
(the "Purchase Contract Agreement"), the Indenture dated as of October 1, 2001
between the Purchaser and The Bank of New York, as supplemented and amended, the
Pledge Agreement dated as of October 1, 2001 between the Purchaser, The Chase
Manhatten Bank and The Bank of New York, as supplemented and amended (the
"Pledge Agreement"), and any other agreement or document that defines the rights
and privileges of the Unit holders (collectively, the "Operative Documents," in
each case as such Operative Documents relate to Units sold by such Seller).

         SECTION 1.3 Acknowledgment of Sellers. Each Seller hereby severally and
expressly acknowledges and agrees from and after the Closing and after giving
effect to the transactions set forth herein that such Seller shall have no
further rights with respect to the Units sold by it and the Operative Documents
with regard to such Units, except rights set forth in this Agreement.

                                   ARTICLE II

                  REPRESENTATIONS AND WARRANTIES OF EACH SELLER

         Each Seller severally (and not jointly) represents and warrants to the
Purchaser as follows:

         SECTION 2.1 Authority; Validity. Such Seller has all requisite power
and authority to execute, deliver, and perform this Agreement. The execution and
delivery of this Agreement by such Seller, the performance by it of its
obligations hereunder, and the consummation of the transactions contemplated
hereby have been duly authorized by all requisite action on the part of Seller.
This Agreement has been duly executed and delivered by such Seller, and
(assuming due authorization, execution, and delivery by the Purchaser), this
Agreement constitutes a legal, valid, and binding obligation of such Seller,
enforceable against such Seller, in accordance with its terms.

         SECTION 2.2 Ownership Interest. Such Seller is the owner of the Units
listed on Schedule A set forth opposite its name, and, upon the Closing, such
Units will be free and clear of all Claims (other than the Claim contemplated
by the Pledge Agreement). For purposes of this Agreement, "Claims" shall mean
any security interest, pledge, hypothecation, mortgage, lien (including, without
limitation, tax liens), violation, charge, lease, license, encumbrance, servient
easement, adverse claim, reversion, reverter, preferential arrangement,
restrictive covenant, condition or restriction of any kind, including without
limitation, any restriction on the use, voting, transfer, receipt of income or
other exercise of any attributes of ownership.
<PAGE>

         SECTION 2.3 Transfer of Interest. Upon consummation of the transactions
contemplated by this Agreement, such Seller will transfer good and marketable
title to its Units to the Purchaser, free and clear of all Claims (other than
the Claim contemplated by the Pledge Agreement and any Claims created by or
through the Purchaser or its affiliates).

         SECTION 2.4 No Conflicts; Consents. The execution, delivery, and
performance of this Agreement by such Seller and the consummation of the
transactions contemplated hereby do not and will not (i) violate, conflict with,
or result in a breach of any provision of the articles or certificate of
incorporation or by-laws or the certificate of formation or limited liability
company agreement (or similar organizational documents) of such Seller,
(ii) conflict with or result in a default (or give rise to any right of
termination, cancellation, or acceleration) under any of the terms, conditions,
or provisions of any note, bond, lease, mortgage, indenture, permit, agreement,
or other instrument or obligation to which such Seller is a party, or by which
such Seller or any of its properties or assets may be bound or affected,
(iii) conflict with or violate any statute, ordinance, law, rule, regulation,
or governmental order applicable to such Seller or its properties or assets,
or (iv) result in the creation or imposition of any Claim upon any property or
assets used or held by such Seller. No waiver, consent, or approval by, any
notification or filing with, or any other action by, any Person is required in
connection with the execution, delivery, and performance by the Seller of this
Agreement or the consummation of the transactions contemplated hereby.

                                  ARTICLE III

                 REPRESENTATIONS AND WARRANTIES OF THE PURCHASER

         The Purchaser represents and warrants to the Sellers as follows:

         SECTION 3.1 Existence and Power. The Purchaser is a corporation duly
organized, validly existing, and in good standing under the laws of the
jurisdiction of its incorporation and has all requisite corporate power and
authority to execute, deliver, and perform this Agreement, to carry out its
obligations hereunder, and to consummate the transactions contemplated hereby.

         SECTION 3.2 Authority; Validity. The execution and delivery of this
Agreement by the Purchaser, the performance by it of its obligations hereunder,
and the consummation of the transactions contemplated hereby have been duly
authorized by all requisite action on the part of the Purchaser. This Agreement
has been duly executed and delivered by the Purchaser, and (assuming due
authorization, execution, and delivery by the Sellers) this Agreement
constitutes a legal, valid, and binding obligation of the Purchaser enforceable
against the Purchaser in accordance with its terms.

         SECTION 3.3 No Conflicts; Consents. The execution, delivery, and
performance of this Agreement by the Purchaser and the consummation of the
transactions contemplated hereby do not and will not (i) violate, conflict with,
or result in a breach of any provision of the articles of incorporation or
by-laws of the Purchaser, (ii) conflict with or result in a default (or give
rise to any right of termination, cancellation, or acceleration) under any of
the terms, conditions, or provisions of any note, bond, lease, mortgage,
indenture, permit, agreement, or other instrument or obligation to which the
Purchaser is a party, or by which the Purchaser or any of its properties or
assets may be bound or affected, (iii) conflict with or violate any statute,
ordinance, law, rule, regulation, or governmental order applicable to the
Purchaser or its properties or assets, or (iv) result in the creation or
imposition of any Claim upon any property or assets used or held by the
Purchaser. No waiver, consent, or approval by, any notification or filing with,
or any other action by, any Person is required in connection with the execution,
delivery, and performance by the Purchaser of this Agreement or the consummation
of the transactions contemplated hereby.
<PAGE>

                                   ARTICLE IV

                              SETTLEMENT AGREEMENT

         SECTION 4.1 Settlement Agreement. There is currently pending in the
Supreme Court of State of New York County of New York, a suit styled Aspen
Partners - Series A, of Aspen Capital Partners, L.P., Deephaven Risk ARB Trading
Ltd, JMG Capital Partners L.P., Pacific Asset Management, L.P., St. Albans
Partners Ltd., Yield Strategies Fund I, L.P., and Yield Strategies Fund II, L.P
vs. TXU Corp.; Index No. 03/603184 (the "Litigation") which includes claims by
Sellers that an event of default and event of termination have occurred under
the terms of the contracts which govern the rights of the parties concerning
the Units.

         SECTION 4.2 Dismissal of the Litigation. The parties recognize and
agree that this Agreement is entered into in order to effect a full settlement
of all claims asserted by the Sellers in the Litigation against Purchaser and
the parties agree that, in connection with this settlement, they will jointly
file with the Court having jurisdiction over the Litigation appropriate
pleadings in order to dismiss the Litigation with prejudice, with the order of
dismissal to provide that costs of court will be taxed against the party
incurring the same and the parties will bear their own attorney's fees.

         SECTION 4.3 Release of Purchaser. Except for claims arising out of a
breach of this Agreement, each Seller, for and on behalf of itself and its
successors and assigns and any and all persons or entities claiming by, through
or under it, hereby RELEASES, DISCHARGES AND ACQUITS, forever and for all
purposes, Purchaser, and Purchaser's affiliated entities, including their
agents, employees, officers, directors, shareholders, partners, insurers,
attorneys, legal representatives, successors and assigns, from and against any
and all liability, and all claims, which such Seller now has, has had or may
have, and all past, present, and future actions, causes of action, claims,
demands, damages, costs, expenses, compensation, and losses (and including
attorneys' fees) of any kind or nature whatsoever, or however described,
whether known or unknown, fixed or contingent, in law or in equity, whether
asserted or unasserted, whether in tort or contract, whether now existing or
accruing in the future, arising out of or related to the purchase, sale or
ownership of the Units sold by such Seller and any and all claims that were
alleged or that could have been alleged against Purchaser and such affiliates
in the Litigation.

         SECTION 4.4 Release of Sellers. Except for claims arising out of a
breach of this Agreement, Purchaser, for and on behalf of itself and its
successors and assigns and any and all persons or entities claiming by, through
or under it, hereby RELEASES, DISCHARGES AND ACQUITS, forever and for all
purposes, each Seller, including their agents, employees, officers, directors,
shareholders, partners, insurers, attorneys, legal representatives, successors
and assigns, from and against any and all liability, and all claims, which
Purchaser now has, has had or may have, and all past, present, and future
actions, causes of action, claims, demands, damages, costs, expenses,
compensation, and losses (and including attorneys' fees) of any kind or nature
whatsoever, or however described, whether known or unknown, fixed or contingent,
in law or in equity, whether asserted or unasserted, whether in tort or
contract, whether now existing or accruing in the future, arising out of or
related to any obligations of Seller to purchase common stock of Purchaser
pursuant to the terms of the Units listed in Schedule A and sold to Purchaser
pursuant to this Agreement, any claims related to Seller's purchase, sale or
ownership of the Units and any and all claims that were alleged or that could
have been alleged against Sellers in the Litigation.
<PAGE>

                                   ARTICLE V

                                  MISCELLANEOUS

         SECTION 5.1 Further Assurances. Each of the parties hereto shall
execute such other documents and instruments of transfer or assignment and do
such other acts or things as may be reasonably required or desirable to carry
out the intent of the parties hereunder and the provisions of this Agreement
and the transactions contemplated hereby.

         SECTION 5.2 Notices, etc. All notices and other communications provided
for hereunder shall be in writing and shall be delivered in person or by courier
service, with written receipt of acceptance returned to sender, or via certified
or registered mail, return receipt requested (postage and charges prepaid), or
by telecopier to each of the parties at the address or telecopier number as
shall be designated by a party in a written notice to the other parties. All
such notices and communications shall, when mailed or telecopied, be effective
when received at the relevant address. Telecopied communications must be
followed by a hard copy sent by registered or certified mail, postage and
charges prepaid.

         SECTION 5.3 Amendments; Waivers. This Agreement may be amended or
modified, and any of the terms or conditions hereof may be waived, only by a
written instrument executed by the parties hereto, or in the case of a waiver,
by the party waiving compliance. Any waiver by any party of any condition, or
of the breach of any provision or term contained in this Agreement, in any one
or more instances, shall not be deemed to be nor construed as a furthering or
continuing waiver of any such condition, or of the breach of any other provision
or term of this Agreement.

         SECTION 5.4 Costs and Expenses. Each party hereto agrees to pay its
own costs and expenses with respect to the transactions contemplated by
this Agreement.

         SECTION 5.5 No Third-Party Beneficiaries. This Agreement is for the
sole benefit of the parties hereto and their successors and assigns and nothing
herein, express or implied, shall give or be construed to give any Person other
than the parties hereto and such successors and assigns any legal or equitable
rights hereunder.

         SECTION 5.6 Governing Law/Consent to Jurisdiction. This Agreement shall
be governed by, and construed in accordance with, the laws of the State of New
York. Each of the parties hereto hereby (i) submits to the exclusive
jurisdiction of any state or federal court sitting in the Borough of Manhattan
of the City of New York for the purpose of any action arising out of or relating
to this Agreement brought by any party hereto, and (ii) irrevocably waives, and
agrees not to assert by way of motion, defense or otherwise, in any such action,
any claim that it is not subject personally to the jurisdiction of the
above-names courts, that its property is exempt or immune from attachment or
execution, that the action is brought in an inconvenient forum, that the venue
of the action is improper, or that this Agreement or the transactions
contemplated by this Agreement may not be enforced in or by any of the
above-named courts.

         SECTION 5.7 Counterparts. This Agreement may be signed in any number of
counterparts, each of which shall be deemed an original and, when taken
together, shall constitute one agreement.

         SECTION 5.8 Headings. Section headings in this Agreement are included
herein for convenience of reference only and shall not constitute a part of
this Agreement for any other purpose.

         SECTION 5.9 Joint and Several Obligations. The obligations of the
respective Sellers set forth herein, including obligations in respect of their
representations and warranties, are several and not joint.

                      [Signatures follow on separate pages]



<PAGE>


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

                         SELLERS:

                                  ASPEN PARTNERS-SERIES A, OF
                                       ASPEN CAPITAL PARTNERS, L.P.


                                  By:  /s/ Nikos Hecht
                                      ----------------------------------------
                                  Name:  Nikos Hecht
                                  Title:
                                         -------------------------------------


                                  DEEPHAVEN RISK ARB TRADING LTD


                                  By:  /s/ Matthew C. Halbower
                                      ----------------------------------------
                                  Name:   Matthew C. Halbower
                                  Title:
                                         -------------------------------------


                                  JMG CAPITAL PARTNERS L.P.


                                  By: /s/  Jonathan Glaser
                                     -----------------------------------------
                                  Name:  Jonathan Glaser
                                  Title:
                                         -------------------------------------


                                  PACIFIC ASSET MANAGEMENT L.L.C.


                                  By:  /s/ Jonathan Glaser
                                     -----------------------------------------
                                  Name:  Jonathan Glaser
                                  Title:
                                         -------------------------------------
                                  *On its own behalf and on behalf of
                                     JMG Triton Offshore Fund, Ltd.


                                  CAMDEN ASSET MANAGEMENT, L.P.


                                  By:  /s/ John Wagner
                                     -----------------------------------------
                                  Name:   John Wagner
                                  Title:
                                         -------------------------------------

<PAGE>

                                  ST. ALBANS PARTNERS, LTD.


                                  By:  /s/  John Wagner
                                     -----------------------------------------
                                  Name:   John Wagner
                                  Title:
                                         -------------------------------------


                                  YIELD STRATEGIES FUND I, L.P.


                                  By:  /s/ John Wagner
                                     -----------------------------------------
                                  Name:   John Wagner
                                  Title:  Partner and Co-CIO


                                  YIELD STRATEGIES FUND II, L.P.


                                  By:  /s/  John Wagner
                                     -----------------------------------------
                                  Name:   John Wagner
                                  Title:  Partner and Co-CIO


<PAGE>


                         PURCHASER:

                                  TXU CORP.


                                  By:  /s/ Kirk R. Oliver
                                      ----------------------------------------
                                  Name:    Kirk R. Oliver
                                  Title:   Treasurer & Assistant Secretary


<PAGE>
<TABLE>
<CAPTION>
                                   SCHEDULE A

                                 Seller            Number of Units       Purchase Price
-----------------------------------------------    ---------------    ------------------
<S>                                                     <C>           <C>
Aspen Partners - Series A, of                           1,460,800     $  69,753,200.00
     Aspen Capital Partners, L.P.

Deephaven Risk Arb Trading Ltd.                         3,564,015     $ 170,181,716.25

JMG Capital Partners, L.P.                                186,950     $   8,926,862.50

JMG Triton Offshore Fund, Ltd.                            186,950     $   8,926,862.50

Accounts managed by                                     1,763,200     $  84,192,800.00
     Camden Asset Management, L.P.

St. Albans Partners Ltd.                                  658,000     $  31,419,500.00

Yield Strategies Fund I, L.P.                             321,000     $  15,327,750.00

Yield Strategies Fund II, L.P.                            325,800     $  15,556,950.00
                                                 ----------------     ----------------

   Total                                                8,466,715     $ 404,285,641.25

</TABLE>

<PAGE>


                                   Schedule B

The Bank of New York
DTC No. 901
Agent No. 26500
Institution ID No. 26657
A/C No. 072635
Re: TXU Corp.

Contact:  Mr. Remo Reale (212.815.2492)