Chesapeake Energy (CHK)

4. Offering by Underwriter. It is understood that the Underwriter proposes to offer the Offered Securities for sale to the public as set forth in the Prospectus.

5. Certain Agreements of the Company. The Company agrees with the Underwriter that:

(a) The Company will file each Statutory Prospectus with the Commission pursuant to and in accordance with Rule 424(b)(2) (or, if applicable and if consented to by the Underwriter, subparagraph (5), such consent not to be unreasonably withheld or delayed) not later than the second business day following the execution and delivery of this Agreement. The Company will also prepare a final term sheet, containing solely the terms of the Offered Securities, in the form set out in Schedule B, and file such term sheet pursuant to Rule 433(d) under the Act within the time required by such Rule and file promptly all other material required to be filed by the Company with the Commission pursuant to Rule 433(d) under the Act.

(b) The Company will advise the Underwriter promptly of any proposal to amend or supplement the Registration Statement or any Statutory Prospectus and will not undertake any such amendment or supplement if the Underwriter reasonably objects in writing thereto; and the Company will also advise the Underwriter promptly of the filing of any such amendment or supplement and of the institution by the Commission of any stop order proceedings in respect of the Registration Statement or of any part thereof and will use its best efforts to prevent the issuance of any such stop order and to obtain as soon as possible its lifting, if issued.

(c) If, at any time when a prospectus relating to the Offered Securities is required to be delivered (whether physically or through compliance with Rule 172 under the Act) in connection with sales by the Underwriter or any dealer, any event occurs as a result of which

10

the Prospectus, as then amended or supplemented would 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, or if it is necessary at any time to amend the Registration Statement or the Prospectus to comply with the Act, the Company promptly will notify the Underwriter of such event and will promptly prepare and file with the Commission, at its own expense, an amendment or supplement which will correct such statement or omission or an amendment which will effect such compliance. Neither the Underwriter’s consent to, nor the Underwriter’s delivery of, any such amendment or supplement shall constitute a waiver of any of the conditions set forth in Section 6 hereof.

(d) As soon as practicable, but not later than 16 months, after the date of this Agreement, the Company will make generally available to its securityholders an earnings statement covering a period of at least 12 months beginning after the later of (i) the effective date of the registration statement relating to the Offered Securities, (ii) the effective date of the most recent post-effective amendment to the Registration Statement to become effective prior to the date of this Agreement and (iii) the date of the Company’s most recent Annual Report on Form 10-K filed with the Commission prior to the date of this Agreement, which will satisfy the provisions of Section 11(a) of the Act.

(e) The Company will furnish to the Underwriter copies of the Registration Statement in the form it became effective (including all exhibits) and of all amendments thereto, any related preliminary prospectus, any related preliminary prospectus supplement, and, so long as a prospectus relating to the Offered Securities is (or but for the exemption in Rule 172 would be required to be) delivered under the Act in connection with sales by the Underwriter or any dealer, the Prospectus and all amendments and supplements to such documents, in each case in such quantities as the Underwriter requests. The Prospectus shall be so furnished on or prior to 3:00 P.M., New York time, on the business day following the execution and delivery of this Agreement. All other documents shall be so furnished as soon as available. The Company will pay the expenses of printing and distributing to the Underwriter all such documents.

(f) The Company will arrange for the qualification of the Offered Securities for sale under the laws of such jurisdictions as the Underwriter designates and will continue such qualifications in effect so long as required for the distribution.

(g) The Company will pay all expenses incidental to the performance of its obligations under this Agreement, for any filing fees and other expenses (including fees and disbursements of counsel) incurred in connection with qualification of the Offered Securities for sale under the laws of such jurisdictions as the Underwriter designates and the printing of memoranda relating thereto, and for expenses incurred in distributing preliminary prospectuses, preliminary prospectus supplements and the Prospectus (including any amendments and supplements thereto) to the Underwriter and for expenses incurred for preparing, printing and distributing any Issuer Free Writing Prospectuses to investors or prospective investors; provided that on the First Closing Date, the Underwriter will reimburse the Company for up to $150,000 of expenses incurred by the Company in the performance of its obligations under this Agreement.

(h) For a period of 90 days after the date of this Agreement, the Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Commission a registration statement under the Act relating to, any additional shares of its common stock or securities convertible into or exchangeable or exercisable for any shares of its common stock, or publicly disclose the intention to make any such offer, sale, pledge, disposition or filing, without the prior written consent of the Underwriter, except (i) grants of employee and director stock options or restricted stock pursuant to the terms of a plan in effect on the date hereof, (ii) issuances of common stock pursuant to the exercise of options, preferred stock, contingent convertible senior notes or warrants outstanding on the date of the

11

initial offering of the Offered Securities, (iii) issuances of common stock in exchange for preferred stock of the Company outstanding on the date of the initial offering of the Offered Securities; (iv) the issuance of Underlying Shares upon conversion of the Offered Securities; and (v) the filing of a registration statement in accordance with a registration rights agreement relating to any preferred stock or contingent convertible senior notes of the Company outstanding on the date of the initial offering of the Offered Securities.

(i) The Company will cause the Underlying Shares to be duly authorized for listing by the New York Stock Exchange on or prior to the First Closing Date and ensure that the Underlying Shares remain authorized for listing following the First Closing Date.

6. Free Writing Prospectuses. The Company represents and agrees that (other than the final term sheet prepared and filed pursuant to Section 5(a) hereto), unless it obtains the prior consent of the Underwriter, and the Underwriter represents and agrees that (other than one or more term sheets relating to the Offered Securities containing customary information and conveyed to purchasers of Offered Securities), unless it obtains the prior consent of the Company, it has not made and will not make any offer relating to the Offered Securities that would constitute an Issuer Free Writing Prospectus, or that would otherwise constitute a “free writing prospectus,” as defined in Rule 405, required to be filed with the Commission. Any such free writing prospectus consented to by the Company and the Underwriter is hereinafter referred to as a “

4. Offering by Underwriters. It is understood that the several Underwriters propose to offer the Offered Securities for sale to the public as set forth in the Prospectus.

5. Certain Agreements of the Company. The Company agrees with the several Underwriters that:

(a) The Company will file the Prospectus with the Commission pursuant to and in accordance with Rule 424(b)(2) (or, if applicable and if consented to by the Representatives, subparagraph (5), such consent not to be unreasonably withheld or delayed) not later than the second business day following the execution and delivery of this Agreement.

(b) The Company will advise the Representatives promptly of any proposal to amend or supplement the Registration Statement or the Prospectus and will afford the Representatives a reasonable opportunity to comment on any such proposed amendment or supplement; and the Company will also advise the Representatives promptly of the filing of any such amendment or supplement and of the institution by the Commission of any stop order proceedings in respect of the Registration Statement or of any part thereof and will use its best efforts to prevent the issuance of any such stop order and to obtain as soon as possible its lifting, if issued.

(c) If, at any time when a prospectus relating to the Offered Securities is required to be delivered under the Act in connection with sales by any Underwriter or dealer, any event occurs as a result of which the Prospectus as then amended or supplemented would 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, or if it is necessary at any time to amend the Prospectus to comply with the Act, the Company promptly will notify the Representatives of such event and will promptly prepare and file with the Commission, at its own expense, an amendment or supplement which will correct such statement or omission or an amendment which will effect such compliance. Neither the Representatives’

[[NYCORP:2535777v10:3639B:09/08/05--09:48 p]]

7

consent to, nor the Underwriters’ delivery of, any such amendment or supplement shall constitute a waiver of any of the conditions set forth in Section 6 hereof.

(d) As soon as practicable, but not later than 16 months, after the date of this Agreement, the Company will make generally available to its securityholders an earnings statement covering a period of at least 12 months beginning after the later of (i) the effective date of the registration statement relating to the Registered Securities, (ii) the effective date of the most recent post-effective amendment to the Registration Statement to become effective prior to the date of this Agreement and (iii) the date of the Company’s most recent Annual Report on Form 10-K filed with the Commission prior to the date of this Agreement, which will satisfy the provisions of Section 11(a) of the Act.

(e) The Company will furnish to the Representatives copies of the Registration Statement in the form it became effective (including all exhibits) and of all amendments thereto, any related preliminary prospectus, any related preliminary prospectus supplement, and, so long as a prospectus relating to the Offered Securities is required to be delivered under the Act in connection with sales by any Underwriter or dealer, the Prospectus and all amendments and supplements to such documents, in each case in such quantities as the Representatives request. The Prospectus shall be so furnished on or prior to 3:00 P.M., New York time, on the business day following the execution and delivery of this Agreement. All other documents shall be so furnished as soon as available. The Company will pay the expenses of printing and distributing to the Underwriters all such documents.

(f) The Company will arrange for the qualification of the Offered Securities for sale under the laws of such jurisdictions as the Representatives designate and will continue such qualifications in effect so long as required for the distribution.

(g) During the period of five years hereafter, the Company will furnish to the Representatives and, upon request, to each of the other Underwriters, as soon as practicable after the end of each fiscal year, a copy of its annual report to stockholders for such year; and the Company will furnish to the Representatives and, upon request, to each of the other Underwriters (i) as soon as available, a copy of each report and any definitive proxy statement of the Company filed with the Commission under the Exchange Act or mailed to stockholders, and (ii) from time to time, such other information concerning the Company as the Representatives may reasonably request other than documents filed and available on the SEC EDGAR system.

(h) The Company will pay all expenses incidental to the performance of its obligations under this Agreement, for any filing fees and other expenses (including fees and disbursements of counsel) incurred in connection with qualification of the Offered Securities for sale under the laws of such jurisdictions as the Representatives designate and the printing of memoranda relating thereto, and for expenses incurred in distributing preliminary prospectuses, preliminary prospectus supplements and the Prospectus (including any amendments and supplements thereto) to the Underwriters; provided that on the First Closing Date, the Underwriters (acting collectively) will reimburse the Company for up to $100,000 of expenses incurred by the Company in the performance of its obligations under this Agreement.

(i) For a period of 90 days after the date of this Agreement, the Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Commission a registration statement under the Act relating to, any additional shares of its common stock or securities convertible into or exchangeable or exercisable for any shares of its common stock, or publicly disclose the intention to make any such offer, sale, pledge, disposition or filing, without the prior written consent of Lehman except (i) grants of employee and director stock options or restricted stock pursuant to the terms of a plan in effect on the date hereof, (ii) issuances of common stock pursuant to the exercise of options, preferred stock or warrants outstanding on the date of the initial offering of the Offered Securities and (iii) issuances of

[[NYCORP:2535777v10:3639B:09/08/05--09:48 p]]

8

common stock in exchange for preferred stock of the Company outstanding on the date of the initial offering of the Offered Securities.

6. Conditions of the Obligations of the Underwriters. The obligations of the several Underwriters to purchase and pay for the Firm Securities on the First Closing Date and the Optional Securities to be purchased on each Optional Closing Date will be subject to the accuracy of the representations and warranties on the part of the Company herein, to the accuracy of the statements of officers of the Company made pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions precedent:

(a) The Representatives shall have received a letter (the “