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Exhibit 31-8

CERTIFICATION PURSUANT TO RULE 13a-14(a)
AND 15d-14(a) OF THE SECURITIES AND EXCHANGE ACT OF
1934



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| | I, J. Barry Mitchell, certify that:                                                                                                                                                                                                                                                                                              
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| | 1. I have reviewed this quarterly report on
    Form 10-Q of Exelon Generation Company, LLC;                                                                                                                                                                                                                                     
|
| | 2. Based on my knowledge, this report does
    not contain any untrue statement of a material fact or omit to
    state a material fact necessary to make the statements made, in
    light of the circumstances under which such statements were
    made, not misleading with respect to the period covered by this
    report;
|
| | 3. Based on my knowledge, the financial
    statements, and other financial information included in this
    report, fairly present in all material respects the financial
    condition, results of operations and cash flows of the
    registrant as of, and for, the periods presented in this report;                       
|
| | 4. The registrants other certifying
    officer and I are responsible for establishing and maintaining
    disclosure controls and procedures (as defined in Exchange Act
    Rules 13a-15(e) and 15d-15(e)) for the registrant and have:                                                                                       



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| | (a) Designed such disclosure controls and
    procedures, or caused such disclosure controls and procedures to
    be designed under our supervision, to ensure that material
    information relating to the registrant, including its
    consolidated subsidiaries, is made known to us by others within
    those entities, particularly during the period in which this
    report is being prepared;
|
| | (b) Evaluated the effectiveness of the
    registrants disclosure controls and procedures and
    presented in this report our conclusions about the effectiveness
    of the disclosure controls and procedures, as of the end of the
    period covered by this report based on such evaluation; and                                                                                                   
|
| | (c) Disclosed in this report any change in
    the registrants internal control over financial reporting
    that occurred during the registrants most recent fiscal
    quarter that has materially affected, or is reasonably likely to
    materially affect, the registrants internal control over
    financial reporting; and                                                                    



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| | 5. The registrants other certifying
    officer and I have disclosed, based on our most recent
    evaluation of internal control over financial reporting, to the
    registrants auditors and the audit committee of the
    registrants board of directors (or persons performing the
    equivalent functions):



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| | (a) All significant deficiencies and
    material weaknesses in the design or operation of internal
    control over financial reporting which are reasonably likely to
    adversely affect the registrants ability to record,
    process, summarize and report financial information; and
|
| | (b) Any fraud, whether or not material, that
    involves management or other employees who have a significant
    role in the registrants internal control over financial
    reporting.                                                                                                   

|                       |  |                                                                                                                        
|---------------------- |  | -----------------------------------------------------------------------------------------------------------------------
|Date: October 27, 2004 |  | /s/ J. BARRY MITCHELLSenior Vice President, Treasurer and Chief Financial
    Officer
    (Principal Financial Officer)