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                                                                     EXHIBIT 4.2

                         EXELON GENERATION COMPANY, LLC

                           6.95% Senior Notes due 2011

                          REGISTRATION RIGHTS AGREEMENT

                                                              New York, New York
                                                                   June 14, 2001

Salomon Smith Barney Inc.
Credit Suisse First Boston Corporation
Banc One Capital Markets, Inc.
   As Representatives of the Initial Purchasers
c/o Salomon Smith Barney Inc.
388 Greenwich Street
New York, New York 10013

Dear Sirs:

          Exelon Generation Company, LLC, a limited liability company organized
under the laws of the Commonwealth of Pennsylvania (the "Company"), proposes to
issue and sell to certain purchasers (the "Initial Purchasers"), upon the terms
set forth in a purchase agreement of even date herewith (the "Purchase
Agreement"), its 6.95% Senior Notes Due 2011 (the "Securities"), relating to the
initial placement of the Securities (the "Initial Placement"). To induce the
Initial Purchasers to enter into the Purchase Agreement and to satisfy a
condition of your obligations thereunder, the Company agrees with you for your
benefit and the benefit of the holders from time to time of the Securities
(including the Initial Purchasers) (each a "Holder" and, together, the
"Holders"), as follows:

          1. DEFINITIONS. Each of the capitalized terms used herein without
definition shall have the meaning set forth in the Purchase Agreement. As used
in this Agreement, the following capitalized defined terms shall have the
following meanings:

          "Act" shall mean the Securities Act of 1933, as amended, and the rules
and regulations of the Commission promulgated thereunder.

          "Affiliate" of any specified Person shall mean any other Person that,
directly or indirectly, is in control of, is controlled by, or is under common
control with, such specified Person. For purposes of this definition, control of
a Person shall mean the power, direct or indirect, to direct or cause the
direction of the management and policies of such Person whether by contract or
otherwise; and the terms "controlling" and "controlled" shall have meanings
correlative to the foregoing.

          "Broker-Dealer" shall mean any broker or dealer registered as such
under the Exchange Act.

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          "Business Day" shall mean any day other than a Saturday, a Sunday or a
legal holiday or a day on which banking institutions or trust companies are
authorized or obligated by law to close in New York City.

          "Commission" shall mean the Securities and Exchange Commission.

          "Exchange Act" shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the Commission promulgated thereunder.

          "Exchange Offer Registration Period" shall mean the one-year period
following the consummation of the Registered Exchange Offer, exclusive of any
period during which any stop order shall be in effect suspending the
effectiveness of the Exchange Offer Registration Statement.

          "Exchange Offer Registration Statement" shall mean a registration
statement of the Company on an appropriate form under the Act with respect to
the Registered Exchange Offer, all amendments and supplements to such
registration statement, including post-effective amendments thereto, in each
case including the Prospectus contained therein, all exhibits thereto and all
material incorporated by reference therein.

          "Exchanging Dealer" shall mean any Holder (which may include any
Initial Purchaser) that is a Broker-Dealer and elects to exchange for New
Securities any Securities that it acquired for its own account as a result of
market-making activities or other trading activities (but not directly from the
Company or any Affiliate of the Company) for New Securities.

          "Final Memorandum" shall have the meaning set forth in the Purchase
Agreement.

          "Holder" shall have the meaning set forth in the preamble hereto.

          "Indenture" shall mean the Indenture relating to the Securities, dated
as of June 1, 2001, between the Company and First Union National Bank, as
trustee, as the same may be amended from time to time in accordance with the
terms thereof.

          "Initial Placement" shall have the meaning set forth in the preamble
hereto.

          "Initial Purchaser" shall have the meaning set forth in the preamble
hereto.

          "Losses" shall have the meaning set forth in Section 6(d) hereof.

          "Majority Holders" shall mean the Holders of a majority of the
aggregate principal amount of Securities registered under a Registration
Statement.

          "Managing Underwriters" shall mean the investment banker or investment
bankers and manager or managers that shall administer an underwritten offering
of the Securities offered pursuant to a Shelf Registration Statement.

          "New Securities" shall mean debt securities of the Company identical
in all

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material respects to the Securities (except that the interest rate step-up
provisions and the transfer restrictions shall be modified or eliminated, as
appropriate) and to be issued under the Indenture.

          "Prospectus" shall mean the prospectus included in any Registration
Statement (including, without limitation, a prospectus that discloses
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 430A under the Act), as amended or
supplemented by any prospectus supplement, with respect to the terms of the
offering of any portion of the Securities or the New Securities covered by such
Registration Statement, and all amendments and supplements thereto and all
material incorporated by reference therein.

          "Purchase Agreement" shall have the meaning set forth in the preamble
hereto.

          "Registered Exchange Offer" shall mean the proposed offer of the
Company to issue and deliver to the Holders of the Securities that are not
prohibited by any law or policy of the Commission from participating in such
offer, in exchange for the Securities, a like aggregate principal amount of the
New Securities.

          "Registration Statement" shall mean any Exchange Offer Registration
Statement or Shelf Registration Statement that covers any of the Securities or
the New Securities pursuant to the provisions of this Agreement, any amendments
and supplements to such registration statement, including post-effective
amendments (in each case including the Prospectus contained therein), all
exhibits thereto and all material incorporated by reference therein.

          "Securities" shall have the meaning set forth in the preamble hereto.

          "Shelf Registration" shall mean a registration effected pursuant to
Section 3 hereof.

          "Shelf Registration Period" has the meaning set forth in Section 3(b)
hereof.

          "Shelf Registration Statement" shall mean a "shelf" registration
statement of the Company pursuant to the provisions of Section 3 hereof which
covers some or all of the Securities or New Securities, as applicable, on an
appropriate form under Rule 415 under the Act, or any similar rule that may be
adopted by the Commission, amendments and supplements to such registration
statement, including post-effective amendments, in each case including the
Prospectus contained therein, all exhibits thereto and all material incorporated
by reference therein.

          "Trustee" shall mean the trustee with respect to the Securities under
the Indenture.

          "Underwriter" shall mean any underwriter of Securities in connection
with an offering thereof under a Shelf Registration Statement.

          2. REGISTERED EXCHANGE OFFER.

          (a) To the extent not prohibited by any applicable law or applicable
     interpretation of the Staff of the Commission, the Company shall use its
     best efforts to consummate the

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     Registered Exchange Offer within 360 days of the date of the original
     issuance of the Securities (or if such 360th day is not a Business Day, the
     next succeeding Business Day).

          (b) Upon the effectiveness of the Exchange Offer Registration
     Statement, the Company shall promptly commence the Registered Exchange
     Offer, it being the objective of such Registered Exchange Offer to enable
     each Holder electing to exchange Securities for New Securities (assuming
     that such Holder is not an Affiliate of the Company, acquires the New
     Securities in the ordinary course of such Holder's business, has no
     arrangements with any Person to participate in the distribution of the New
     Securities and is not prohibited by any law or policy of the Commission
     from participating in the Registered Exchange Offer ) to trade such New
     Securities from and after their receipt without any limitations or
     restrictions under the Act and without material restrictions under the
     securities laws of a substantial proportion of the several states of the
     United States.

          (c) In connection with the Registered Exchange Offer, the Company
     shall:

               (i) mail to each Holder a copy of the Prospectus forming part of
          the Exchange Offer Registration Statement, together with an
          appropriate letter of transmittal and related documents;

               (ii) keep the Registered Exchange Offer open for not less than 20
          Business Days and not more than 30 Business Days after the date notice
          thereof is mailed to the Holders (or, in each case, longer if required
          by applicable law);

               (iii) use its best efforts to keep the Exchange Offer
          Registration Statement continuously effective under the Act,
          supplemented and amended as required, under the Act to ensure that it
          is available for sales of New Securities by Exchanging Dealers during
          the Exchange Offer Registration Period;

               (iv) utilize the services of a depositary for the Registered
          Exchange Offer with an address in the Borough of Manhattan in New York
          City, which may be the Trustee or an Affiliate of the Trustee;

               (v) permit Holders to withdraw tendered Securities at any time
          prior to the close of business, New York time, on the last Business
          Day on which the Registered Exchange Offer is open;

               (vi)  prior to effectiveness of the Exchange Offer Registration
          Statement, provide a supplemental letter to the Commission (A) stating
          that the Company is conducting the Registered Exchange Offer in
          reliance on the position of the Commission in EXXON CAPITAL HOLDINGS
          CORPORATION (pub. avail. May 13, 1988), MORGAN STANLEY AND CO., INC.
          (pub. avail. June 5, 1991); and (B) including a representation that
          the Company has not entered into any arrangement or understanding with
          any Person to distribute the New Securities to be received in the
          Registered Exchange Offer and that, to the best of the Company's
          information and belief, each Holder participating in the Registered
          Exchange Offer is

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          acquiring the New Securities in the ordinary course of business and
          has no arrangement or understanding with any Person to participate in
          the distribution of the New Securities; and

               (vii) comply in all respects with all applicable laws.

          (d) As soon as practicable after the close of the Registered Exchange
     Offer, the Company shall:

               (i)   accept for exchange all Securities tendered and not validly
          withdrawn pursuant to the Registered Exchange Offer;

               (ii)  deliver to the Trustee for cancellation in accordance with
          Section 4(s) all Securities so accepted for exchange; and

               (iii) cause the Trustee promptly to authenticate and deliver to
          each Holder of Securities a principal amount of New Securities equal
          to the principal amount of the Securities of such Holder so accepted
          for exchange.

          (e) Each Holder hereby acknowledges and agrees that any Broker-Dealer
     and any such Holder using the Registered Exchange Offer to participate in a
     distribution of the New Securities (x) could not under Commission policy as
     in effect on the date of this Agreement rely on the position of the
     Commission in MORGAN STANLEY AND CO., INC. (pub. avail. June 5, 1991) and
     EXXON CAPITAL HOLDINGS CORPORATION (pub. avail. May 13, 1988), as
     interpreted in the Commission's letter to SHEARMAN & STERLING dated July 2,
     1993 and similar no-action letters; and (y) must comply with the
     registration and prospectus delivery requirements of the Act in connection
     with any secondary resale transaction must be covered by an effective
     registration statement containing the selling security holder information
     required by Item 507 or 508, as applicable, of Regulation S-K under the Act
     if the resales are of New Securities obtained by such Holder in exchange
     for Securities acquired by such Holder directly from the Company or one of
     its Affiliates. Accordingly, each Holder participating in the Registered
     Exchange Offer shall be required to represent to the Company that, at the
     time of the consummation of the Registered Exchange Offer:

               (i)   any New Securities received by such Holder will be acquired
          in the ordinary course of business;

               (ii) such Holder will have no arrangement or understanding with
          any Person to participate in the distribution of the Securities or the
          New Securities within the meaning of the Act; and

               (iii) such Holder is not an Affiliate of the Company.

          (f) If any Initial Purchaser determines that it is not eligible to
     participate in the Registered Exchange Offer with respect to the exchange
     of Securities constituting any portion of an unsold allotment, at the
     request of such Initial Purchaser, the Company shall issue and deliver to
     such Initial Purchaser or the Person purchasing New Securities

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     registered under a Shelf Registration Statement as contemplated by Section
     3 hereof from such Initial Purchaser, in exchange for such Securities, a
     like principal amount of New Securities. The Company shall use its best
     efforts to cause the CUSIP Service Bureau to issue the same CUSIP number
     for such New Securities as for New Securities issued pursuant to the
     Registered Exchange Offer.

          3. SHELF REGISTRATION.

          (a) If (i) due to any change in law or applicable interpretations
          thereof by the Commission's staff, the Company determines upon advice
          of its outside counsel that it is not permitted to effect the
          Registered Exchange Offer as contemplated by Section 2 hereof; or

               (ii)  for any other reason the Registered Exchange Offer is not
          consummated within 360 days of the date hereof;

               (iii) any Initial Purchaser so requests with respect to
          Securities that are not eligible to be exchanged for New Securities in
          the Registered Exchange Offer and that are held by it following
          consummation of the Registered Exchange Offer;

               (iv)  any Holder (other than an Initial Purchaser) is not
          eligible to participate in the Registered Exchange Offer; or

               (v) in the case of any Initial Purchaser that participates in the
          Registered Exchange Offer or acquires New Securities pursuant to
          Section 2(f) hereof, such Initial Purchaser does not receive freely
          tradeable New Securities in exchange for Securities constituting any
          portion of an unsold allotment (it being understood that (x) the
          requirement that an Initial Purchaser deliver a Prospectus containing
          the information required by Item 507 or 508 of Regulation S-K under
          the Act in connection with sales of New Securities acquired in
          exchange for such Securities shall result in such New Securities being
          not "freely tradeable"; and (y) the requirement that an Exchanging
          Dealer deliver a Prospectus in connection with sales of New Securities
          acquired in the Registered Exchange Offer in exchange for Securities
          acquired as a result of market-making activities or other trading
          activities shall not result in such New Securities being not "freely
          tradeable"), the Company shall effect a Shelf Registration Statement
          in accordance with subsection (b) below.

          (b) (i) To the extent not prohibited by any applicable law or
          applicable interpretation of the Staff of the Commission, the Company
          shall as promptly as practicable (but in no event more than 60 days
          after so required or requested pursuant to this Section 3), file with
          the Commission and thereafter shall use its best efforts to cause to
          be declared effective under the Act a Shelf Registration Statement
          relating to the offer and sale of the Securities or the New
          Securities, as applicable, by the Holders thereof from time to time in
          accordance with the methods of distribution elected by such Holders
          and set forth in such Shelf Registration Statement; PROVIDED, HOWEVER,
          that no Holder (other than an Initial

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          Purchaser) shall be entitled to have the Securities held by it covered
          by such Shelf Registration Statement unless such Holder agrees in
          writing to be bound by all of the provisions of this Agreement
          applicable to such Holder; and provided further, that with respect to
          New Securities received by an Initial Purchaser in exchange for
          Securities constituting any portion of an unsold allotment, the
          Company may, if permitted by current interpretations by the
          Commission's staff, file a post-effective amendment to the Exchange
          Offer Registration Statement containing the information required by
          Item 507 or 508 of Regulation S-K, as applicable, in satisfaction of
          its obligations under this subsection with respect thereto, and any
          such Exchange Offer Registration Statement, as so amended, shall be
          referred to herein as, and governed by the provisions herein
          applicable to, a Shelf Registration Statement.

               (ii) The Company shall use its best efforts to keep the Shelf
          Registration Statement continuously effective, supplemented and
          amended as required by the Act, in order to permit the Prospectus
          forming part thereof to be usable by Holders for a period of two years
          from the date the Shelf Registration Statement is declared effective
          by the Commission or such shorter period that will terminate when all
          the Securities or New Securities, as applicable, covered by the Shelf
          Registration Statement have been sold pursuant to the Shelf
          Registration Statement (in any such case, such period being called the
          "Shelf Registration Period"). The Company shall be deemed not to have
          used its best efforts to keep the Shelf Registration Statement
          effective during the requisite period if it voluntarily takes any
          action that would result in Holders of Securities covered thereby not
          being able to offer and sell such Securities during that period,
          unless (A) such action is required by applicable law; or (B) such
          action is taken by the Company in good faith and for valid business
          reasons (not including avoidance of the Company's obligations
          hereunder), including the acquisition or divestiture of assets, so
          long as the Company promptly thereafter complies with the requirements
          of Section 4(k) hereof, if applicable.

          4. ADDITIONAL REGISTRATION PROCEDURES. In connection with any Shelf
Registration Statement and, to the extent applicable, any Exchange Offer
Registration Statement, the following provisions shall apply.

          (a)  The Company shall:

               (i) furnish to you, not less than five Business Days prior to the
          filing thereof with the Commission, a copy of any Exchange Offer
          Registration Statement and any Shelf Registration Statement, and each
          amendment thereof and each amendment or supplement, if any, to the
          Prospectus included therein (including all documents incorporated by
          reference therein after the initial filing) and shall use its best
          efforts to reflect in each such document, when so filed with the
          Commission, such comments as you reasonably propose;

               (ii) include the information set forth in Annex A hereto on the
          facing page of the Exchange Offer Registration Statement, in Annex B
          hereto in the forepart

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          of the Exchange Offer Registration Statement in a section setting
          forth details of the Exchange Offer, in Annex C hereto in the
          underwriting or plan of distribution section of the Prospectus
          contained in the Exchange Offer Registration Statement, and in Annex D
          hereto in the letter of transmittal delivered pursuant to the
          Registered Exchange Offer;

          (iii) if requested by an Initial Purchaser, include the information
          required by Item 507 or 508 of Regulation S-K, as applicable, in the
          Prospectus contained in the Exchange Offer Registration Statement; and

          (iv) in the case of a Shelf Registration Statement, include the names
          of the Holders that propose to sell Securities pursuant to the Shelf
          Registration Statement as selling security holders.

          (b) The Company shall advise you, the Holders of Securities covered by
     any Shelf Registration Statement and any Exchanging Dealer under any
     Exchange Offer Registration Statement that has provided in writing to the
     Company a telephone or facsimile number and address for notices, and, if
     requested by you or any such Holder or Exchanging Dealer, shall confirm
     such advice in writing (which notice pursuant to clauses (ii)-(v) hereof
     shall be accompanied by an instruction to suspend the use of the Prospectus
     until the Company shall have remedied the basis for such suspension):

               (i) when a Registration Statement and any amendment thereto has
          been filed with the Commission and when the Registration Statement or
          any post-effective amendment thereto has become effective;

               (ii) of any request by the Commission for any amendment or
          supplement to the Registration Statement or the Prospectus or for
          additional information;

               (iii) of the issuance by the Commission of any stop order
          suspending the effectiveness of the Registration Statement or the
          initiation of any proceedings for that purpose;

               (iv) of the receipt by the Company of any notification with
          respect to the suspension of the qualification of the securities
          included therein for sale in any jurisdiction or the initiation of any
          proceeding for such purpose; and

               (v) of the happening of any event that requires any change in the
          Registration Statement or the Prospectus so that, as of such date, the
          statements therein are not misleading and do not omit to state a
          material fact required to be stated therein or necessary to make the
          statements therein (in the case of the Prospectus, in the light of the
          circumstances under which they were made) not misleading.

          (c) The Company shall use its best efforts to obtain the withdrawal of
     any order suspending the effectiveness of any Registration Statement or the
     qualification of the securities therein for sale in any jurisdiction at the
     earliest possible time.

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          (d) The Company shall furnish to each Holder of Securities covered by
     any Shelf Registration Statement, without charge, at least one copy of such
     Shelf Registration Statement and any post-effective amendment thereto,
     including all material incorporated therein by reference, and, if the
     Holder so requests in writing, all exhibits thereto (including exhibits
     incorporated by reference therein).

          (e) The Company shall, during the Shelf Registration Period, deliver
     to each Holder of Securities covered by any Shelf Registration Statement,
     without charge, as many copies of the Prospectus (including each
     preliminary Prospectus) included in such Shelf Registration Statement and
     any amendment or supplement thereto as such Holder may reasonably request.
     The Company consents to the use of the Prospectus or any amendment or
     supplement thereto by each of the selling Holders of securities in
     connection with the offering and sale of the securities covered by the
     Prospectus, or any amendment or supplement thereto, included in the Shelf
     Registration Statement.

          (f) The Company shall furnish to each Exchanging Dealer which so
     requests, without charge, at least one copy of the Exchange Offer
     Registration Statement and any post-effective amendment thereto, including
     all material incorporated by reference therein, and, if the Exchanging
     Dealer so requests in writing, all exhibits thereto (including exhibits
     incorporated by reference therein).

          (g) The Company shall promptly deliver to each Initial Purchaser, each
     Exchanging Dealer and each other Person required to deliver a Prospectus
     during the Exchange Offer Registration Period, without charge, as many
     copies of the Prospectus included in such Exchange Offer Registration
     Statement and any amendment or supplement thereto as any such Person may
     reasonably request. The Company consents to the use of the Prospectus or
     any amendment or supplement thereto by any Initial Purchaser, any
     Exchanging Dealer and any such other Person that may be required to deliver
     a Prospectus following the Registered Exchange Offer in connection with the
     offering and sale of the New Securities covered by the Prospectus, or any
     amendment or supplement thereto, included in the Exchange Offer
     Registration Statement.

          (h) Prior to the Registered Exchange Offer or any other offering of
     Securities pursuant to any Registration Statement, the Company shall
     arrange, if necessary, for the qualification of the Securities or the New
     Securities for sale under the laws of such jurisdictions as any Holder
     shall reasonably request and will maintain such qualification in effect so
     long as required; provided that in no event shall the Company be obligated
     to qualify to do business in any jurisdiction where it is not then so
     qualified or to take any action that would subject it to service of process
     in suits, other than those arising out of the Initial Placement, the
     Registered Exchange Offer or any offering pursuant to a Shelf Registration
     Statement, in any such jurisdiction where it is not then so subject.

          (i) The Company shall cooperate with the Holders of Securities to
     facilitate the timely preparation and delivery of certificates representing
     New Securities or Securities to be issued or sold pursuant to any
     Registration Statement free of any restrictive legends and in such
     denominations and registered in such names as Holders may request.

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          (j) Upon the occurrence of any event contemplated by subsections
     (b)(ii) through (v) above, the Company shall promptly prepare a
     post-effective amendment to the applicable Registration Statement or an
     amendment or supplement to the related Prospectus or file any other
     required document so that, as thereafter delivered to Initial Purchasers of
     the Securities included therein, the Prospectus will not include an untrue
     statement of a material fact or omit to state any material fact necessary
     to make the statements therein, in the light of the circumstances under
     which they were made, not misleading. In such circumstances, the period of
     effectiveness of the Exchange Offer Registration Statement provided for in
     Section 2 and the Shelf Registration Statement provided for in Section 3(b)
     shall each be extended by the number of days from and including the date of
     the giving of a notice of suspension pursuant to Section 4(b) to and
     including the date when the Initial Purchasers, the Holders of the
     Securities and any known Exchanging Dealer shall have received such amended
     or supplemented Prospectus pursuant to this Section.

          (k) Not later than the effective date of any Registration Statement,
     the Company shall provide a CUSIP number for the Securities or the New
     Securities, as the case may be, registered under such Registration
     Statement and provide the Trustee with printed certificates for such
     Securities or New Securities, in a form eligible for deposit with The
     Depository Trust Company.

          (l) The Company shall make generally available to its security holders
     as soon as practicable after the effective date of the applicable
     Registration Statement an earnings statement satisfying the provisions of
     Section 11(a) of the Act.

          (m) The Company shall cause the Indenture to be qualified under the
     Trust Indenture Act in a timely manner.

          (n) The Company may require each Holder of Securities to be sold
     pursuant to any Shelf Registration Statement to furnish to the Company such
     information regarding the Holder and the distribution of such Securities as
     the Company may from time to time reasonably require for inclusion in such
     Registration Statement. The Company may exclude from such Shelf
     Registration Statement the Securities of any Holder that unreasonably fails
     to furnish such information within a reasonable time after receiving such
     request and the Company shall be under no further obligations to such
     Holder to include such Holder in a Shelf Registration Statement.

          (o) In the case of any Shelf Registration Statement, the Company shall
     enter into such and take all other appropriate actions (including if
     requested an underwriting agreement in customary form) in order to expedite
     or facilitate the registration or the disposition of the Securities, and in
     connection therewith, if an underwriting agreement is entered into, cause
     the same to contain indemnification provisions and procedures no less
     favorable than those set forth in Section 6 (or such other provisions and
     procedures acceptable to the Majority Holders and the Managing
     Underwriters, if any, with respect to all parties to be indemnified
     pursuant to Section 6.

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          (p)  In the case of any Shelf Registration Statement, the Company
     shall:

               (i) subject to execution of a confidentiality agreement in form
          and substance reasonably acceptable to the Company and the Holders,
          make reasonably available for inspection by the Holders of Securities
          to be registered thereunder, any underwriter participating in any
          disposition pursuant to such Registration Statement, and any attorney,
          accountant or other agent retained by the Holders or any such
          underwriter all relevant financial and other records, pertinent
          corporate documents and properties of the Company and its
          subsidiaries;

               (ii) cause the Company's officers, directors and employees to
          supply all relevant information reasonably requested by the Holders or
          any such underwriter, attorney, accountant or agent in connection with
          any such Registration Statement as is customary for similar due
          diligence examinations; provided, however, that any information that
          is designated in writing by the Company, in good faith, as
          confidential at the time of delivery of such information shall be kept
          confidential by the Holders or any such underwriter, attorney,
          accountant or agent, unless such disclosure is made in connection with
          a court proceeding or required by law, or such information becomes
          available to the public generally or through a third party without an
          accompanying obligation of confidentiality;

               (iii) make such representations and warranties to the Holders of
          Securities registered thereunder and the underwriters, if any, in
          form, substance and scope as are customarily made by issuers to
          underwriters in underwritten offerings and covering matters including,
          but not limited to, those set forth in the Purchase Agreement;

               (iv) obtain opinions of counsel to the Company and updates
          thereof (which counsel and opinions (in form, scope and substance)
          shall be reasonably satisfactory to the Managing Underwriters, if any)
          addressed to each selling Holder and the underwriters, if any,
          covering such matters as are customarily covered in opinions requested
          in underwritten offerings and such other matters as may be reasonably
          requested by such Holders and underwriters;

               (v) obtain "cold comfort" letters and updates thereof from the
          independent certified public accountants of the Company (and, if
          necessary, any other independent certified public accountants of any
          subsidiary of the Company or of any business acquired by the Company
          for which financial statements and financial data are, or are required
          to be, included in the Registration Statement), addressed to each
          selling Holder of Securities registered thereunder and the
          underwriters, if any, in customary form and covering matters of the
          type customarily covered in "cold comfort" letters in connection with
          primary underwritten offerings; and

               (vi) deliver such documents and certificates as may be reasonably
          requested by the Majority Holders and the Managing Underwriters, if
          any,

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          including those to evidence compliance with Section 4(k) and with any
          customary conditions contained in the underwriting agreement or other
          agreement entered into by the Company.

          The actions set forth in clauses (iii), (iv), (v) and (vi) of this
Section shall be performed at each closing under any underwriting or similar
agreement as and to the extent required thereunder.

          (q) If a Registered Exchange Offer is to be consummated, upon delivery
     of the Securities by Holders to the Company (or to such other Person as
     directed by the Company) in exchange for the New Securities, the Company
     shall mark, or caused to be marked, on the Securities so exchanged that
     such Securities are being canceled in exchange for the New Securities. In
     no event shall the Securities be marked as paid or otherwise satisfied.

          (r) The Company will use its best efforts (i) if the Securities have
     been rated prior to the initial sale of such Securities pursuant to the
     Purchase Agreement, to confirm such ratings will apply to the Securities or
     the New Securities, as the case may be, covered by a Registration
     Statement; or (ii) if the Securities were not previously rated, to cause
     the Securities covered by a Registration Statement to be rated with at
     least one nationally recognized statistical rating agency, if so requested
     by Majority Holders with respect to the related Registration Statement or
     by any Managing Underwriters.

          (s) In the event that any Broker-Dealer shall underwrite any
     Securities or participate as a member of an underwriting syndicate or
     selling group or "assist in the distribution" (within the meaning of the
     Rules of Fair Practice and the By-Laws of the National Association of
     Securities Dealers, Inc.) thereof, whether as a Holder of such Securities
     or as an underwriter, a placement or sales agent or a broker or dealer in
     respect thereof, or otherwise, assist such Broker-Dealer in complying with
     the requirements of such Rules and By-Laws, including, without limitation,
     by:

               (i) if such Rules or By-Laws shall so require, engaging a
          "qualified independent underwriter" (as defined in such Rules) to
          participate in the preparation of the Registration Statement, to
          exercise usual standards of due diligence with respect thereto and, if
          any portion of the offering contemplated by such Registration
          Statement is an underwritten offering or is made through a placement
          or sales agent, to recommend the yield of such Securities;

               (ii) indemnifying any such qualified independent underwriter to
          the extent of the indemnification of underwriters provided in Section
          6 hereof; and

               (iii) providing such information to such Broker-Dealer as may be
          required in order for such Broker-Dealer to comply with the
          requirements of such Rules.

          (t) The Company shall use its best efforts to take all other steps
     necessary to effect the registration of the Securities or the New
     Securities, as the case may be, covered by a Registration Statement.

                                      -12-
<Page>

          5. REGISTRATION EXPENSES. The Company shall bear all expenses incurred
in connection with the performance of its obligations under Sections 2, 3 and 4
hereof and, in the event of any Shelf Registration Statement, will reimburse the
Holders for the reasonable fees and disbursements of one firm or counsel
designated by the Majority Holders to act as counsel for the Holders in
connection therewith, and, in the case of any Exchange Offer Registration
Statement, will reimburse the Initial Purchasers for the reasonable fees and
disbursements of their counsel incurred in connection with their review of the
Exchange Offer Registration Statement.

          6. INDEMNIFICATION AND CONTRIBUTION.

          (a) The Company agrees to indemnify and hold harmless each Holder of
     Securities or New Securities, as the case may be, covered by any
     Registration Statement (including each Initial Purchaser and, with respect
     to any Prospectus delivery as contemplated in Section 4(h) hereof, each
     Exchanging Dealer), the directors, officers, employees and agents of each
     such Holder and each Person who controls any such Holder within the meaning
     of either the Act or the Exchange Act against any and all losses, claims,
     damages or liabilities, joint or several, to which they or any of them may
     become subject under the Act, the Exchange Act or other Federal or state
     statutory law or regulation, at common law or otherwise, insofar as such
     losses, claims, damages or liabilities (or actions in respect thereof)
     arise out of or are based upon any untrue statement or alleged untrue
     statement of a material fact contained in the Registration Statement as
     originally filed or in any amendment thereof, or in any preliminary
     Prospectus or the Prospectus, or in any amendment thereof or supplement
     thereto, or arise out of or are based upon the omission or alleged omission
     to state therein a material fact required to be stated therein or necessary
     to make the statements therein not misleading, and agrees to reimburse each
     such indemnified party, as incurred, for any legal or other expenses
     reasonably incurred by them in connection with investigating or defending
     any such loss, claim, damage, liability or action; provided, however, that
     the Company will not be liable in any case to the extent that any such
     loss, claim, damage or liability arises out of or is based upon any such
     untrue statement or alleged untrue statement or omission or alleged
     omission made therein in reliance upon and in conformity with written
     information furnished to the Company by or on behalf of any such Holder
     specifically for inclusion therein. This indemnity agreement will be in
     addition to any liability which the Company may otherwise have.

          The Company also agrees to indemnify or contribute as provided in
     Section 6(d) to Losses of each and any person deemed an "underwriter",
     under the Act or the rules and regulations thereunder, of Securities or New
     Securities, as the case may be, registered under a Shelf Registration
     Statement, their directors, officers, employees or agents and each Person
     who controls such underwriter on substantially the same basis as that of
     the indemnification of the Initial Purchasers and the selling Holders
     provided in this Section 6(a) and shall, if requested by any Holder, enter
     into an underwriting agreement reflecting such agreement, as provided in
     Section 4(p) hereof.

          (b) Each Holder of securities covered by a Registration Statement
     (including each Initial Purchaser and, with respect to any Prospectus
     delivery as contemplated in Section 4(h) hereof, each Exchanging Dealer)
     severally agrees to indemnify and hold

                                      -13-
<Page>

     harmless the Company each of its directors each of its officers who signs
     such Registration Statement and each Person who controls the Company within
     the meaning of either the Act or the Exchange Act, to the same extent as
     the foregoing indemnity from the Company to each such Holder, but only with
     reference to written information relating to such Holder furnished to the
     Company by or on behalf of such Holder specifically for inclusion in the
     documents referred to in the foregoing indemnity. This indemnity agreement
     will be in addition to any liability which any such Holder may otherwise
     have.

          (c) Promptly after receipt by an indemnified party under this Section
     6 or notice of the commencement of any action, such indemnified party will,
     if a claim in respect thereof is to be made against the indemnifying party
     under this Section, notify the indemnifying party in writing of the
     commencement thereof; but the failure so to notify the indemnifying party
     (i) will not relieve it from liability under paragraph (a) or (b) above
     unless and to the extent it did not otherwise learn of such action and such
     failure results in the forfeiture by the indemnifying party of substantial
     rights and defenses; and (ii) will not, in any event, relieve the
     indemnifying party from any obligations to any indemnified party other than
     the indemnification obligation provided in paragraph (a) or (b) above. The
     indemnifying party shall be entitled to appoint counsel of the indemnifying
     party's choice at the indemnifying party's expense to represent the
     indemnified party in any action for which indemnification is sought (in
     which case the indemnifying party shall not thereafter be responsible for
     the fees and expenses of any separate counsel retained by the indemnified
     party or parties except as set forth below); provided, however, that such
     counsel shall be satisfactory to the indemnified party. Notwithstanding the
     indemnifying party's election to appoint counsel to represent the
     indemnified party in an action, the indemnified party shall have the right
     to employ separate counsel (including local counsel), and the indemnifying
     party shall bear the reasonable fees, costs and expenses of such separate
     counsel if (i) the use of counsel chosen by the indemnifying party to
     represent the indemnified party would present such counsel with a conflict
     of interest; (ii) the actual or potential defendants in, or targets of, any
     such action include both the indemnified party and the indemnifying party
     and the indemnified party shall have reasonably concluded that there may be
     legal defenses available to it and/or other indemnified parties which are
     different from or additional to those available to the indemnifying party;
     (iii) the indemnifying party shall not have employed counsel satisfactory
     to the indemnified party to represent the indemnified party within a
     reasonable time after notice of the institution of such action; or (iv) the
     indemnifying party shall authorize the indemnified party to employ separate
     counsel at the expense of the indemnifying party. An indemnifying party
     will not, without the prior written consent of the indemnified parties,
     settle or compromise or consent to the entry of any judgment with respect
     to any pending or threatened claim, action, suit or proceeding in respect
     of which indemnification or contribution may be sought hereunder (whether
     or not the indemnified parties are actual or potential parties to such
     claim or action) unless such settlement, compromise or consent includes an
     unconditional release of each indemnified party from all liability arising
     out of such claim, action, suit or proceeding.

          (d) In the event that the indemnity provided in paragraph (a) or (b)
     of this Section is for any reason held to be unenforceable by an
     indemnified party although applicable in accordance with its terms, then
     each applicable indemnifying party shall

                                      -14-
<Page>

     have a joint and several obligation to contribute to the aggregate losses,
     claims, damages and liabilities (including legal or other expenses
     reasonably incurred in connection with investigating or defending same)
     (collectively "Losses") to which such indemnified party may be subject in
     such proportion as is appropriate to reflect the relative benefits received
     by such indemnifying party, on the one hand, and such indemnified party, on
     the other hand, from the Initial Placement and the Registration Statement
     which resulted in such Losses; provided, however, that in no case shall any
     Initial Purchaser or any subsequent Holder of any Security or New Security
     be responsible, in the aggregate, for any amount in excess of the purchase
     discount or commission applicable to such Security, or in the case of a New
     Security, applicable to the Security that was exchangeable into such New
     Security, as set forth on the cover page of the Final Memorandum, nor shall
     any underwriter be responsible for any amount in excess of the underwriting
     discount or commission applicable to the securities purchased by such
     underwriter under the Registration Statement which resulted in such Losses.
     If the allocation provided by the immediately preceding sentence is
     unavailable for any reason, the indemnifying party and the indemnified
     party shall contribute in such proportion as is appropriate to reflect not
     only such relative benefits but also the relative fault of such
     indemnifying party, on the one hand, and such indemnified party, on the
     other hand, in connection with the statements or omissions which resulted
     in such Losses as well as any other relevant equitable considerations.
     Benefits received by the Company shall be deemed to be equal to the sum of
     (x) the total net proceeds from the Initial Placement (before deducting
     expenses) as set forth on the cover page of the Final Memorandum and (y)
     the total amount of additional interest which the Company was not required
     to pay as a result of registering the securities covered by the
     Registration Statement which resulted in such Losses. Benefits received by
     the Initial Purchasers shall be deemed to be equal to the total purchase
     discounts and commissions as set forth on the cover page of the Final
     Memorandum, and benefits received by any other Holders shall be deemed to
     be equal to the value of receiving Securities or New Securities, as
     applicable, registered under the Act. Benefits received by any underwriter
     shall be deemed to be equal to the total underwriting discounts and
     commissions, as set forth on the cover page of the Prospectus forming a
     part of the Registration Statement which resulted in such Losses. Relative
     fault shall be determined by reference to, among other things, whether any
     alleged untrue statement or omission relates to information provided by the
     indemnifying party, on the one hand, or by the indemnified party, on the
     other hand, the intent of the parties and their relative knowledge, access
     to information and opportunity to correct or prevent such untrue statement
     or omission. The parties agree that it would not be just and equitable if
     contribution were determined by pro rata allocation (even if the Holders
     were treated as one entity for such purpose) or any other method of
     allocation which does not take account of the equitable considerations
     referred to above. Notwithstanding the provisions of this paragraph (d), no
     Person guilty of fraudulent misrepresentation (within the meaning of
     Section 11(f) of the Act) shall be entitled to contribution from any Person
     who was not guilty of such fraudulent misrepresentation. For purposes of
     this Section, each Person who controls a Holder within the meaning of
     either the Act or the Exchange Act and each director, officer, employee and
     agent of such Holder shall have the same rights to contribution as such
     Holder, and each Person who controls the Company within the meaning of
     either the Act or the Exchange Act, each officer of the Company who

                                      -15-
<Page>

     shall have signed the Registration Statement and each director of the
     Company shall have the same rights to contribution as the Company, subject
     in each case to the applicable terms and conditions of this paragraph (d).

          (e) The provisions of this Section will remain in full force and
     effect, regardless of any investigation made by or on behalf of any Holder
     or the Company or any of the officers, directors or controlling Persons
     referred to in this Section hereof, and will survive the sale by a Holder
     of securities covered by a Registration Statement.

          7. UNDERWRITTEN REGISTRATIONS.

          (a) If any of the Securities or New Securities, as the case may be,
     covered by any Shelf Registration Statement are to be sold in an
     underwritten offering, the Managing Underwriters shall be selected by the
     Majority Holders.

          (b) No Person may participate in any underwritten offering pursuant to
     any Shelf Registration Statement, unless such Person (i) agrees to sell
     such Person's Securities or New Securities, as the case may be, on the
     basis reasonably provided in any underwriting arrangements approved by the
     Persons entitled hereunder to approve such arrangements; and (ii) completes
     and executes all questionnaires, powers of attorney, indemnities,
     underwriting agreements and other documents reasonably required under the
     terms of such underwriting arrangements.

          8. NO INCONSISTENT AGREEMENTS. The Company has not, as of the date
hereof, entered into, nor shall it, on or after the date hereof, enter into, any
agreement with respect to its securities that is inconsistent with the rights
granted to the Holders herein or otherwise conflicts with the provisions hereof.

          9. AMENDMENTS AND WAIVERS. The provisions of this Agreement, including
the provisions of this sentence, may not be amended, qualified, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given, unless the Company has obtained the written consent of the
Majority Holders (or, after the consummation of any Registered Exchange Offer in
accordance with Section 2 hereof, of New Securities); provided that, with
respect to any matter that directly or indirectly affects the rights of any
Initial Purchaser hereunder, the Company shall obtain the written consent of
each such Initial Purchaser against which such amendment, qualification,
supplement, waiver or consent is to be effective. Notwithstanding the foregoing
(except the foregoing proviso), a waiver or consent to departure from the
provisions hereof with respect to a matter that relates exclusively to the
rights of Holders whose Securities or New Securities, as the case may be, are
being sold pursuant to a Registration Statement and that does not directly or
indirectly affect the rights of other Holders may be given by the Majority
Holders, determined on the basis of Securities or New Securities, as the case
may be, being sold rather than registered under such Registration Statement.

          10. NOTICES. All notices and other communications provided for or
permitted hereunder shall be made in writing by hand-delivery, first-class mail,
telex, telecopier or air courier guaranteeing overnight delivery:

                                      -16-
<Page>

          (a) if to a Holder, at the most current address given by such holder
     to the Company in accordance with the provisions of this Section, which
     address initially is, with respect to each Holder, the address of such
     Holder maintained by the Registrar under the Indenture, with a copy in like
     manner to Salomon Smith Barney Inc.;

          (b) if to you, initially at the respective addresses set forth in the
     Purchase Agreement; and

          (c) if to the Company, initially at its address set forth in the
     Purchase Agreement.

          All such notices and communications shall be deemed to have been duly
     given when received.

          The Initial Purchasers or the Company by notice to the other parties
     may designate additional or different addresses for subsequent notices or
     communications.

          11. SUCCESSORS. This Agreement shall inure to the benefit of and be
binding upon the successors and assigns of each of the parties, including,
without the need for an express assignment or any consent by the Company
thereto, subsequent Holders of Securities and the New Securities. The Company
hereby agrees to extend the benefits of this Agreement to any Holder of
Securities and the New Securities, and any such Holder may specifically enforce
the provisions of this Agreement as if an original party hereto.

          12. COUNTERPARTS. This agreement may be in signed counterparts, each
of which shall an original and all of which together shall constitute one and
the same agreement.

          13. HEADINGS. The headings used herein are for convenience only and
shall not affect the construction hereof.

          14. APPLICABLE LAW. This Agreement shall be governed by and construed
in accordance with the laws of the State of New York applicable to contracts
made and to be performed in the State of New York.

          15. SEVERABILITY. In the event that any one of more of the provisions
contained herein, or the application thereof in any circumstances, is held
invalid, illegal or unenforceable in any respect for any reason, the validity,
legality and enforceability of any such provision in every other respect and of
the remaining provisions hereof shall not be in any way impaired or affected
thereby, it being intended that all of the rights and privileges of the parties
shall be enforceable to the fullest extent permitted by law.

          16. SECURITIES HELD BY THE COMPANY, ETC. Whenever the consent or
approval of Holders of a specified percentage of principal amount of Securities
or New Securities is required hereunder, Securities or New Securities, as
applicable, held by the Company or its Affiliates (other than subsequent Holders
of Securities or New Securities if such subsequent Holders are deemed to be
Affiliates solely by reason of their holdings of such Securities or New
Securities) shall not be counted in determining whether such consent or approval
was given by the Holders of such required percentage.

                                      -17-
<Page>

                            [signature page follows]

                                      -18-
<Page>

               If the foregoing is in accordance with your understanding of our
agreement, please sign and return to us the enclosed duplicate hereof, whereupon
this letter and your acceptance shall represent a building agreement among the
Company and the several Initial Purchasers.

                                Very truly yours,

                                EXELON GENERATION COMPANY, LLC

                                By: EXELON VENTURES COMPANY, LLC, a
                                    Delaware limited liability company, as the
                                    Managing Member
                                    By: EXELON CORPORATION, a
                                        Pennsylvania corporation, as the
                                        Managing Member


                                        By: /s/ J. Barry Mitchell
                                            Name: J. Barry Mitchell
                                            Title:

The foregoing Agreement is hereby confirmed and accepted as of the date first
above written.

SALOMON SMITH BARNEY INC.
CREDIT SUISSE FIRST BOSTON
  CORPORATION
BANC ONE CAPITAL MARKETS, INC.

  By: SALOMON SMITH BARNEY INC.


      By: /s/ Henry A. Clark
          Name:  Henry A. Clark
          Title: Managing Director

For themselves and the other several
Initial Purchasers named in Schedule I
to the Purchase Agreement.

<Page>

                                                                         ANNEX A

               Each Broker-Dealer that receives New Securities for its own
account pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such New Securities. The Letter of
Transmittal states that by so acknowledging and by delivering a prospectus, a
Broker-Dealer will not be deemed to admit that it is an "underwriter: within the
meaning of the Securities Act. This Prospectus, as it may be amended or
supplemented from time to time, may be used by a Broker-Dealer in connection
with resales of New Securities received in exchange for Securities where such
Securities were acquired by such Broker-Dealer as a result of market-making
activities or other trading activities. The Company has agreed that, starting on
the Expiration Date (as defined herein) and ending on the close of business one
year after the Expiration Date, it will make this Prospectus available to any
Broker-Dealer for use in connection with any such resale. See "Plan of
Distribution".

<Page>

                                                                         ANNEX B

               Each Broker-Dealer that receives New Securities for its own
account in exchange for Securities, where such Securities were acquired by such
Broker-Dealer as a result of market-making activities or other trading
activities, must acknowledge that it will deliver a prospectus in connection
with any resale of such New Securities. See "Plan of Distribution".

<Page>

                                                                         ANNEX C

                              PLAN OF DISTRIBUTION

               Each Broker-Dealer that receives New Securities for its own
account pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such New Securities. This
Prospectus, as it may be amended or supplemented from time to time, may be used
by a Broker-Dealer in connection with resales of New Securities received in
exchange for Securities where such Securities were acquired as a result of
market-making activities or other trading activities. The Company has agreed
that, starting on the Expiration Date and ending on the close of business one
year after the Expiration Date, it will make this Prospectus, as amended or
supplemented, available to any Broker-Dealer for use in connection with any such
resale. In addition, until __________, 20___, all dealers effecting transactions
in the New Securities may be required to deliver a prospectus.

               The Company will not receive any proceeds from any sale of New
Securities by brokers-dealers. New Securities received by Broker-Dealers for
their own account pursuant to the Exchange Offer may be sold from time to time
in one or more transactions in the over-the-counter market, in negotiated
transactions, through the writing of options on the New Securities or a
combination of such methods of resale, at market prices prevailing at the time
of resale, at prices related to such prevailing market prices or negotiated
prices. Any such resale may be made directly to purchasers or to or through
brokers or dealers who may receive compensation in the form of commissions or
concessions from any such Broker-Dealer and/or the purchasers of any such New
Securities. Any Broker-Dealer that resales New Securities that were received by
it for its own account pursuant to the Exchange Offer and any broker or dealer
that participates in a distribution of such New Securities may be deemed to be
an "underwriter" within the meaning of the Securities Act and any profit of any
such resale of New Securities and any commissions or concessions received by any
such Persons may be deemed to be underwriting compensation under the Securities
Act. The Letter of Transmittal states that by acknowledging that it will deliver
and by delivering a prospectus, a Broker-Dealer will not be deemed to admit that
it is an "underwriter" within the meaning of the Securities Act.

               For a period of one year after the Expiration Date, the Company
will promptly send additional copies of this Prospectus and any amendment or
supplement to this Prospectus to any Broker-Dealer that requests such documents
in the Letter of Transmittal. The Company has agreed to pay all expenses
incident to the Exchange Offer (including the expenses of one counsel for the
holder of the Securities) other than commissions or concessions of any brokers
or dealers and will indemnify the holders of the Securities (including any
Broker-Dealers) against certain liabilities, including liabilities under the
Securities Act.

<Page>

                                                                         ANNEX D

RIDER A

CHECK HERE IF YOU ARE A BROKER-DEALER AND WISH TO RECEIVE 10 ADDITIONAL COPIES
OF THE PROSPECTUS AND 10 COPIES OF ANY AMENDMENTS OR SUPPLEMENTS THERETO.

Name:     ______________________________________
Address:  ______________________________________
          ______________________________________

RIDER B

If the undersigned is not a Broker-Dealer, the undersigned represents that it
acquired the New Securities in the ordinary course of its business, it is not
engaged in, and does not intend to engage in, a distribution of New Securities
and it has not arrangements or understandings with any Person to participate in
a distribution of the New Securities. If the undersigned is a Broker-Dealer that
will receive New Securities for its own account in exchange for Securities, it
represents that the Securities to be exchange for New Securities were acquired
by it as a result of market-making activities or other trading activities and
acknowledges that it will deliver a prospectus in connection with any resale of
such New Securities; however, by so acknowledging and by delivering a
prospectus, the undersigned will not be deemed to admit that it is an
"underwriter" within the meaning of the Securities Act.