EXHIBIT 10.1

FIRST AMENDMENT TO

LETTER OF CREDIT AND REIMBURSEMENT AGREEMENT

THIS FIRST AMENDMENT TO LETTER OF CREDIT AND REIMBURSEMENT AGREEMENT (this
“Amendment”), dated as of June 27, 2008, is among COMMONWEALTH EDISON COMPANY, a
corporation organized and existing under the laws of the State of Illinois (the
“Company”), the financial institutions signatory hereto, and BARCLAYS BANK PLC,
NEW YORK BRANCH, as administrative agent (the “Administrative Agent”).

RECITALS

A. The Company, the Administrative Agent and the Banks are party to that certain
Letter of Credit and Reimbursement Agreement dated as of May 9, 2008 (as
amended, restated or otherwise modified from time to time, the “Reimbursement
Agreement”). Unless otherwise specified herein, capitalized terms used in this
Amendment shall have the meanings ascribed to them by the Reimbursement
Agreement.

B. The Company, the Administrative Agent and the undersigned Banks wish to amend
the Reimbursement Agreement on the terms and conditions set forth below.

NOW, THEREFORE, in consideration of the mutual execution hereof and other good
and valuable consideration, the parties hereto agree as follows:

1. Amendments. Upon the Effective Date (as defined below), the Reimbursement
Agreement shall be amended as follows:

(a) The second and third paragraphs of the “Preliminary Statements” of the
Reimbursement Agreement are hereby amended by restating them in their entirety
as follows:

The Issuer and the Company desire to refinance one or more (or portions thereof)
of the Existing Bonds through the issuance by the Issuer of one or more new
series of Pollution Control Revenue Refunding Bonds (Commonwealth Edison
Company) as more particularly described in the definition of “Bonds” herein.

The Company also desires that the L/C Issuers provide a Letter of Credit
pursuant to this Agreement to replace a certain letter of credit issued by
JPMorgan Chase Bank, N.A. under the Credit Agreement in connection with the
series of Bonds referred to as the “$91,000,000 Pollution Control Revenue
Refunding Bonds (Commonwealth Edison Company Project) Series 2008F” (the
“Replacement Letter of Credit”).

In order to enhance the Bonds by providing a source of payment when due of the
principal of and interest on and the purchase price of the Bonds, the L/C
Issuers will provide the Letters of Credit (including, the Replacement Letter of
Credit) pursuant to this Agreement to facilitate such payments.

(b) Section 1.01 of the Reimbursement Agreement is hereby amended by restating
the definition of “Bonds” contained therein as follows:

“Bonds” means, collectively, the $50,000,000 Pollution Control Revenue Refunding
Bonds (Commonwealth Edison Company Project) Series 2008D, the

--------------------------------------------------------------------------------

$49,830,000 Pollution Control Revenue Refunding Bonds (Commonwealth Edison
Company Project) Series 2008E and the $91,000,000 Pollution Control Revenue
Refunding Bonds (Commonwealth Edison Company Project) Series 2008F; provided
that the initial principal balance of any series of Bonds may be less than the
amount stated above.

2. Representations and Warranties of the Company. The Company represents and
warrants that:

(a) The execution, delivery and performance by the Company of this Amendment are
within the Company’s powers, have been duly authorized by all necessary
organizational action on the part of the Company, and do not and will not
contravene (i) the organizational documents of the Company, (ii) applicable law
or (iii) any contractual or legal restriction binding on or affecting the
properties of the Company or any Subsidiary.

(b) No authorization or approval or other action by, and no notice to or filing
with, any governmental authority or regulatory body is required for the due
execution, delivery and performance by the Company of this Amendment, except any
order that has been duly obtained and is (x) in full force and effect and
(y) sufficient for the purposes hereof.

(c) This Amendment is a legal, valid and binding obligation of the Company,
enforceable against the Company in accordance with its terms, except as the
enforceability thereof may be limited by equitable principles or bankruptcy,
insolvency, reorganization, moratorium or similar laws affecting the enforcement
of creditors’ rights generally.

(d) Each of the representations and warranties contained in the Reimbursement
Agreement is true and correct on and as of the date hereof as if made on the
date hereof.

(e) No Default or Event of Default has occurred and is continuing.

3. Effective Date. This Amendment shall become effective (the “Effective Date”)
upon satisfaction of the following conditions precedent:

(a) The Administrative Agent shall have received (i) a counterpart of this
Amendment signed on behalf of the Company and the Majority Banks or (ii) written
evidence (which may include facsimile or other electronic transmission of a
signed signature page of this Amendment) that each such party hereto has signed
a counterpart of this Amendment.

(b) The representations and warranties set forth in Section 2 hereof are true
and correct.

4. Reference to and Effect Upon the Reimbursement Agreement.

(a) Except as specifically amended and supplemented hereby, the Reimbursement
Agreement shall remain in full force and effect to the extent in effect
immediately prior to this Amendment and is hereby ratified and confirmed.

(b) The execution, delivery and effectiveness of this Amendment shall not
operate as a waiver of any right, power or remedy of the Administrative Agent or
any Bank under the Reimbursement Agreement, nor constitute a waiver of any
provision of the Reimbursement Agreement, except as specifically set forth
herein.

 

- 2 -

--------------------------------------------------------------------------------

5. Governing Law. THIS AMENDMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

6. Counterparts. This Amendment may be executed in any number of counterparts
and by different parties hereto in separate counterparts, each of which when so
executed shall be deemed to be an original and all of which taken together shall
constitute one and the same agreement.

[Signature Pages Follow]

 

- 3 -

--------------------------------------------------------------------------------

IN WITNESS WHEREOF, the parties have executed this First Amendment to Letter of
Credit and Reimbursement Agreement as of the date first above written.

 

COMMONWEALTH EDISON COMPANY By:  

/s/ Robert K. McDonald

Name:   Robert K. McDonald Title:  

Senior Vice President, Chief Financial Officer,

Treasurer and Chief Risk Officer

--------------------------------------------------------------------------------

BARCLAYS BANK PLC, as Administrative Agent and
as a Bank By:  

/s/ Gary B. Wenslow

Name:   Gary B. Wenslow Title:   Associate Director

--------------------------------------------------------------------------------

THE ROYAL BANK OF SCOTLAND PLC, as a Bank By:  

/s/ Emily Freedman

Name:   Emily Freedman Title:   Vice President

--------------------------------------------------------------------------------

BANK OF AMERICA, N.A., as a Bank By:  

/s/ Patrick Martin

Name:   Patrick Martin Title:   Vice President

--------------------------------------------------------------------------------

THE BANK OF NOVA SCOTIA, as a Bank By:  

/s/ Frank Sandler

Name:   Frank Sandler Title:   Managing Director

--------------------------------------------------------------------------------

SUNTRUST BANK, as a Bank By:  

/s/ Andrew Johnson

Name:   Andrew Johnson Title:   Director

--------------------------------------------------------------------------------

JPMORGAN CHASE BANK, N.A., as a Bank By:  

/s/ Michael De Forge

Name:   Michael De Forge Title:   Executive Director