UNDERWRITING AGREEMENT

Exhibit 1.1

$300,000,000

GATX CORPORATION

4.750% SENIOR NOTES DUE 2012

UNDERWRITING AGREEMENT

September 21, 2009

Citigroup Global Markets Inc.
390 Greenwich Street
New York, New York 10013

Banc of America Securities LLC
Bank of America Tower
One Bryant Park
New York, NY 10036

  As Representatives of the Underwriters
  Listed in Schedule I hereto

Ladies and Gentlemen:

          GATX Corporation, a New York corporation (the “ Company ”), proposes to issue and sell to the several Underwriters listed in Schedule I hereto (the “ Underwriters ”) for whom you are acting as representatives (the “ Representatives ”) $300,000,000 aggregate principal amount of its 4.750% Senior Notes due 2012 (the “ Securities ”) pursuant to the provisions of an Indenture dated as of February 6, 2008 between the Company, as issuer, and U.S. Bank National Association, as Trustee (the “ Indenture ”) and an Officer’s Certificate to be dated on or about September 24, 2009.

          This is to confirm our agreement concerning the Underwriters’ purchase of the Securities in the respective aggregate principal amounts set forth in Schedule I hereto.

          The Company has filed with the Securities and Exchange Commission (the “ Commission ”) an automatic shelf registration statement including a prospectus relating to the Securities under the Securities Act of 1933, as amended (the “ Securities Act ”). The term “ Registration Statement ” means the Registration Statement on Form S-3 (Reg. No. 333-145521), including the exhibits and schedules thereto, as amended to the date of this Underwriting Agreement (the “ Agreement ”), and any Prospectus deemed part of such registration statement pursuant to Rule 430B under the Securities Act, as amended on each Effective Date (as defined below), and, in the event any post-effective amendment thereto becomes effective prior to the Closing Date, shall also mean such registration statement as so

amended, as the case may be. The term “ Basic Prospectus ” means the prospectus included in the Registration Statement, as amended to the date of this Agreement. The term “ Prospectus ” means the Basic Prospectus together with the prospectus supplement specifically relating to the Securities (the “ Prospectus Supplement ”), as filed with, or transmitted for filing to, the Commission after the Execution Time (as defined below) pursuant to Rule 424. The term “ preliminary prospectus ” means a preliminary prospectus supplement specifically referring to the Securities, together with the Basic Prospectus, which is used prior to the filing of the Prospectus. As used herein, the terms “Registration Statement,” “Basic Prospectus,” “Prospectus” and “preliminary prospectus” shall include in each case the documents, if any, incorporated by reference therein. The term “ Issuer Free Writing Prospectus ” means an issuer free writing prospectus, as defined in Rule 433 under the Securities Act. The term “ Free Writing Prospectus ” means a free writing prospectus, as defined in Rule 405 under the Securities Act. The term “ Disclosure Package ” shall mean the preliminary prospectus, all Issuer Free Writing Prospectuses, if any, identified on Schedule II hereto, the final term sheet prepared and filed pursuant to Section 6(b) below, and all other Free Writing Prospectus that the parties hereto shall hereafter expressly agree in writing to treat as part of the Disclosure Package. The term “supplement,” “amendment” and “amend” as used herein shall include all documents deemed to be incorporated by reference in the Registration Statement, the Prospectus, the preliminary prospectus or any Issuer Free Writing Prospectus that are filed subsequent to the date of the Basic Prospectus by the Company with the Commission pursuant to the Securities Exchange Act of 1934, as amended (the “ Exchange Act ”). The term “ Effective Date ” means each date and time that the Registration Statement, and any post-effective amendment or amendments thereto became or becomes effective. The term “ Execution Time ” shall mean the date and time that this Agreement is executed and delivered by the parties thereto.

     1. The Company represents and warrants to and agrees with each of the Underwriters that:

     (a) The Company has prepared and filed with the Commission the Registration Statement, including the Basic Prospectus, for registration under the Securities Act of the offering and sale of the Securities. Such Registration Statement became effective upon filing; no stop order suspending the effectiveness of the Registration Statement is in effect, and no proceedings for such purpose are pending before or, to the Company’s knowledge, threatened by the Commission. The Company has filed with the Commission, as part of an amendment to the Registration Statement or pursuant to Rule 424(b) under the Securities Act, a preliminary prospectus supplement relating to the Securities. The Company will file with the Commission a final prospectus supplement relating to the Securities in accordance with Rule 424(b) under the Securities Act. As filed, such final prospectus supplement shall contain all information required by the Securities Act and the rules and regulations of the Commission thereunder.

     (b) (i) Each document, if any, filed or to be filed pursuant to the Exchange Act and incorporated by reference in the Disclosure Package and the Prospectus, complied or will comply when so filed in all material respects with the Exchange Act and the rules and regulations of the Commission thereunder and will be timely filed as required thereby, (ii) each part of the Registration Statement, when such part became effective, did not contain and each such part, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading, (iii) the Registration Statement, on the latest Effective Date, and the Prospectus, as of its date, complied and, as amended or supplemented, if applicable, will comply in all material respects with the Securities Act, the Exchange Act, the Trust Indenture Act of 1939, as amended (the “ Trust Indenture Act ”) and the applicable rules and regulations of the Commission thereunder, (iv) the Prospectus, as of its date, did not contain and as of the Closing Date, as amended or supplemented, if applicable, will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, and (v)

the Disclosure Package, as of the Execution Time, does not contain any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided that the representations and warranties set forth in this Section 1(b) do not apply (x) to statements or omissions in the Registration Statement, the Disclosure Package or the Prospectus based upon information concerning the Underwriters furnished to the Company in writing by the Underwriters expressly for use therein, it being understood and agreed that the only such information furnished to the Company consists of the information described as such in Section 8(b) below, or (y) to that part of the Registration Statement that constitutes the Statement of Eligibility and Qualification (Form T-1) under the Trust Indenture Act, of the Trustee.

     (c) At the earliest time after the filing of the Registration Statement that the Company or other offering participant made a bona fide offer (within the meaning of Rule 164(h)(2) under the Securities Act) of the Securities, the Company was not and is not an Ineligible Issuer (as defined in Rule 405 under the Securities Act), without taking account of any determination by the Commission pursuant to Rule 405 under the Securities Act that it is not necessary that the Company be considered an Ineligible Issuer.

     (d) Each Issuer Free Writing Prospectus and the final term sheet prepared and filed pursuant to Section 6(b) below does not include any information that conflicts with the information contained or incorporated by reference in the Registration Statement, including any prospectus supplement deemed to be a part thereof that has not been superseded or modified, it being understood and agreed that the foregoing does not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Company by the Underwriters, it being understood and agreed that the only such information furnished to the Company by the Underwriters consists of the information described as such in Section 8(b) below.

     (e) (i) At the time of filing the Registration Statement, (ii) at the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Securities Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Sections 13 or 15(d) of the Exchange Act or form of prospectus), (iii) at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c) under the Securities Act) made any offer relating to the Securities in reliance on the exemption in Rule 163, and (iv) at the Execution Time (with such date being used as the determination date for purposes of this clause (iv)) the Company was or is (as the case may be) a “well-known seasoned issuer” as defined in Rule 405 under the Securities Act. The Company agrees to pay the fees required by the Commission relating to the Securities within the time required by Rule 456(b)(1) under the Securities Act without regard to the proviso therein and otherwise in accordance with Rules 456(b) and 457(r) under the Securities Act.

     (f) The Company has been duly incorporated, is validly existing as a corporation in good standing under the laws of the State of New York, has the corporate power and authority to own its property and to conduct its business as described in the Disclosure Package and the Prospectus, and is duly qualified to transact business and is in good standing in each jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect (as defined below).

     (g) Each subsidiary of the Company that is a “significant subsidiary” as defined in Rule 405 under the Securities Act (a “ Significant Subsidiary ”) has been duly incorporated, is validly existing as a corporation in good standing under the laws of the jurisdiction of its incorporation, has the corporate power and authority to own its property and to conduct its business as described in the Disclosure Package and the Prospectus, and is duly qualified to transact business and is in good standing in each

jurisdiction in which the conduct of its business or its ownership or leasing of property requires such qualification, except to the extent that the failure to be so qualified or be in good standing would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

     (h) This Agreement has been duly authorized, executed and delivered by the Company.

     (i) The Indenture has been duly authorized, executed and delivered by the Company and, assuming the due authorization, execution and delivery by the Trustee, constitutes a valid and binding agreement of the Company enforceable in accordance with its terms except as the enforceability thereof may be limited by (i) bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance or other similar laws affecting creditor’s rights and remedies generally from time to time in effect and (ii) general principles of equity (whether considered in a proceeding in equity or at law) and an implied covenant of good faith and fair dealing (the “ Enforceability Exceptions ”). The Indenture has been duly qualified under the Trust Indenture Act and will conform in all material respects to the descriptions thereof in the Disclosure Package and the Prospectus.

     (j) The Securities have been duly authorized and, when executed and authenticated in accordance with the provisions of the Indenture and delivered to and duly paid for by the Underwriters, as provided in this Agreement, will conform in all material respects to the descriptions thereof in the Disclosure Package and the Prospectus, will be entitled to the benefits of the Indenture and will be valid and legally binding obligations of the Company, enforceable against the Company in accordance with their terms except as the enforceability thereof may be limited by the Enforceability Exceptions.

     (k) The execution and delivery by the Company of, and the performance by the Company of its obligations under, this Agreement and the Indenture and the issuance and sale of the Securities by the Company will not (i) constitute a default under any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the property or assets of the Company or any of its subsidiaries is subject (each, an “ Existing Instrument ”), (ii) result in any violation of the certificate of incorporation or bylaws of the Company, (iii) conflict with or constitute a breach of, or default under, or result in the creation or imposition of any lien, charge or encumbrance upon any of the property or assets of the Company or any of its subsidiaries pursuant to any Existing Instrument or (iv) result in any violation of any law, regulation, judgment, order or decree of any governmental body, agency or court having jurisdiction over the Company or any of its subsidiaries, except in each case of clauses (i), (iii) and (iv), for such defaults, conflicts, breaches, liens, charges, encumbrances or violations as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; and, to the best of the Company’s knowledge, no consent, approval or authorization of any governmental body or agency is required for the performance by the Company of its obligations under this Agreement, the Indenture or the Securities, except such as have been or will be obtained prior to the Closing Date under the Securities Act, the Exchange Act and the Trust Indenture Act and such as may be required under the securities or Blue Sky laws of the various states in connection with the offer and sale of the Securities.

     (l) Since the date of the most recent audited financial statements in the Disclosure Package and the Prospectus, there has not been any material adverse change, or any development that would reasonably be expected to result in a material adverse change, in the financial condition, stockholders’ equity, results of operations, business or properties of the Company and its subsidiaries, taken as a whole, whether or not arising in the ordinary course of business (referred to as a “ Material Adverse Change ” or “ Material Adverse Effect ”) from that set forth in the Disclosure Package and the Prospectus.

     (m) There are no legal or governmental proceedings pending or, to the best of the Company’s knowledge, threatened to which the Company or any of its subsidiaries is a party or to which any of the properties of the Company or any of its subsidiaries is subject that are required to be described in the Registration Statement or the Disclosure Package or the Prospectus and are not so described or, to the best of the Company’s knowledge, any statutes, regulations, contracts or other documents that are required to be described in the Registration Statement, the Disclosure Package or the Prospectus or to be filed as an exhibit to the Registration Statement that are not described or filed as required.

     (n) The Company and each of its Significant Subsidiaries have all necessary consents, authorizations, approvals, orders, certificates and permits of and from, and have made all declarations and filings with, all federal, state, local and other governmental authorities, all self-regulatory organizations and all courts and other tribunals, to own, lease, license and use its properties and assets and to conduct their business in the manner described in the Disclosure Package and the Prospectus, as then amended or supplemented, except to the extent that the failure to obtain or file would not reasonably be expected to have a Material Adverse Effect.

     (o) Ernst & Young LLP, whose reports have been included or incorporated by reference in the Disclosure Package and the Prospectus, is an independent registered public accounting firm within the applicable rules and regulations adopted by the Commission and the Public Accounting Oversight Board (United States) and as required by the Securities Act and the rules and regulations thereunder.

     (p) The financial statements included or incorporated by reference in the Registration Statement, the Disclosure Package and the Prospectus present fairly in all material respects the financial condition and results of operations of the Company and its subsidiaries taken as a whole, at the dates and for the periods indicated, and have been prepared in conformity with generally accepted accounting principles applied on a consistent basis throughout the periods involved.

     (q) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Disclosure Package and the Prospectus, the Company will not be required to register as, an “investment company” as such term is defined in the Investment Company Act of 1940, as amended;

     (r) The Company and its subsidiaries maintain a system of internal control over financial reporting (as such term is defined in Rule 13a-15(f) under the Exchange Act) and are not aware of any material weakness in their internal controls over financial reporting.

     (s) The Company and its subsidiaries maintain “disclosure controls and procedures” (as such term is defined in Rule 13a-15(e) under the Exchange Act); such disclosure controls and procedures are effective.

     (t) The Company and its subsidiaries are (i) in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety, the environment or hazardous or toxic substances or wastes, pollutants or contaminants (“ Environmental Laws ”), (ii) have received and are in compliance with all permits, licenses or other approvals required of them under applicable Environmental Laws to conduct their respective businesses and (iii) have not received notice of any actual or potential liability under any environmental law, except where such non-compliance with Environmental Laws, failure to receive required permits, licenses or other approvals, or liability would not, individually or in the aggregate, have a Material Adverse Change, except as set forth in or contemplated in the Disclosure Package and the Prospectus (exclusive of any supplement thereto).

          2. The Company agrees to issue and sell the Securities to the Underwriters as hereinafter provided, and each Underwriter, upon the basis of the representations and warranties herein contained and subject to the conditions hereinafter stated, agrees, severally and not jointly, to purchase from the Company the aggregate principal amount of Securities set forth opposite such Underwriter’s name in Schedule I hereto at the purchase price (the “ Purchase Price ”) in U.S. Dollars equal to 99.943% of the principal amount of the Securities plus accrued interest thereon, if any, from the “Closing Date” (as defined in Section 4 hereof) to the date of payment and delivery. The Company agrees to pay to Citigroup Global Markets Inc. and Banc of America Securities LLC (on behalf of the Underwriters) an aggregate commission of 0.40% (40 basis points) on the aggregate principal amount of Securities purchased hereunder. Such payment shall be made simultaneously with the payment by the Underwriters of the Purchase Price as set forth in Section 4.  Payment of such compensation shall be made by Federal funds check or other immediately available funds to the order of Citigroup Global Markets Inc. on behalf of the Underwriters.

          3. The Company is advised by the Representatives that the Underwriters propose to make a public offering of their respective portions of the Underwriters’ Securities as soon after this Agreement is entered into as in the Representatives’ judgment is advisable. The terms of the public offering of the Underwriters’ Securities are set forth in the Disclosure Package and the Prospectus.

          4. Payment for the Securities by the Underwriters shall be made by wire transfer in immediately available funds to the account specified by the Company to the Representatives on or about September 24, 2009 or at such other time on the same or such other date, as the Representatives and the Company may agree upon in writing. The time and date of such payment are referred to herein as the “ Closing Date ”. As used herein, the term “ Business Day ” means any day other than a day on which banks are permitted or required to be closed in New York City.

          Payment for the Securities shall be made against delivery of one or more global certificates for the Securities in the aggregate amount set forth in Schedule I hereto, each of which will be deposited with U.S. Bank National Association, as custodian for DTC and registered in the name of a nominee of DTC. Forms of such certificates will be made available for inspection by the Underwriters at Mayer Brown LLP, not later than 12:00 p.m., New York, New York time, or at such other location as the Representatives and the Company shall agree, on the Business Day prior to the Closing Date.

          5. The several obligations of the Underwriters hereunder are subject to the accuracy of the representations and warranties on the part of the Company contained herein as of the Execution Time and the Closing Date, to the accuracy of the statements of the Company made in any certificates pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions:

     (a) Subsequent to the execution and delivery of this Agreement and prior to the Closing Date:

     (b) The Representatives shall have received on the Closing Date an opinion from Deborah A. Golden, Senior Vice President and General Counsel of GATX Corporation, dated the Closing Date, in form and substance satisfactory to the Representatives, to the effect set forth in Exhibit A hereto.

     (c) The Representatives shall have received on the Closing Date an opinion, dated the Closing Date, of Mayer Brown LLP, counsel for the Company, in form and substance satisfactory to the Representatives, to the effect set forth in Exhibit B hereto

     (d) The Representatives shall have received on the Closing Date an opinion of Winston & Strawn LLP, counsel for the Underwriters, dated the Closing Date, with respect to the issuance and sale of the Securities, the Indenture, the Registration Statement, the Disclosure Package, the Prospectus (together with any supplement thereto) and other related matters as the Representatives may reasonably require, and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.

     (e) The Representatives shall have received, on the Closing Date, a certificate, dated the Closing Date and signed by an executive officer of the Company, to the effect set forth in Section 5(a)(i) above and to the effect that (i) the representations and warranties of the Company contained in this Agreement are true and correct as of the Closing Date; (ii) the Company has complied with all of the agreements and satisfied all of the conditions on its part to be performed or satisfied hereunder on or before the Closing Date; (iii) since the date of the most recent financial statements included or incorporated by reference in the Disclosure Package and in the Prospectus, as amended or supplemented as of the Execution Time, there has been no Material Adverse Change from that set forth in the Disclosure Package, as so amended or supplemented and in the Prospectus; and (iv) no stop order suspending the effectiveness of the Registration Statement has been issued and no proceedings for that purpose have been instituted or, to the Company’s knowledge, threatened. The officer signing and delivering such certificate may rely upon the best of his or her knowledge as to proceedings threatened.

     (f) The Representatives shall have received on the date hereof and confirmed on the Closing Date, a letter dated the date hereof or the Closing Date, as applicable, in form and substance reasonably satisfactory to the Representatives, from Ernst & Young LLP, independent registered public accounting firm of the Company, containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial statements and certain financial information contained in or incorporated by reference into the Registration Statement, the Disclosure Package and the Prospectus.

     (g) If filing of the Prospectus, or any supplement thereto, is required pursuant to Rule 424(b) under the Securities Act, the Prospectus and any such supplement shall have been filed in the manner and within the time period required by Rule 424(b); the final term sheet contemplated by Section 6(b) hereof, and any other material required to be filed by the Company pursuant to Rule 433(d) under the Securities Act, shall have been filed with the Commission within the applicable time periods prescribed for such filings by Rule 433 under the Securities Act; and no stop order suspending the effectiveness of the Registration Statement shall have been issued and no proceedings for that purpose shall have been instituted or, to the Company’s knowledge, threatened.

     (h) On or prior to the Closing Date the Company shall have furnished to each Underwriter such further certificates and documents as such Underwriter shall reasonably request pursuant to Section 6(i) below.

          6. In further consideration of the agreements of the Underwriters contained in this Agreement, the Company covenants as follows:

     (a) Prior to the termination of the offering of the Securities pursuant to this Agreement, the Company will not file any amendment or supplement to the Registration Statement or the Basic Prospectus (including any Prospectus Supplement relating to the Securities) unless the Company has previously furnished to the Representatives a copy thereof for its review and will not file any such proposed amendment or supplement to which the Representatives reasonably object; provided that the foregoing requirement shall not apply to any of the Company’s periodic filings with the Commission required to be filed pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act, which filings the Company will cause to be timely filed with the Commission and copies of which filings the Company will cause to be delivered to the Representatives upon written request therefor promptly after being filed with the Commission. Subject to the foregoing sentence, the Company will promptly cause each Prospectus Supplement to be filed with the Commission in accordance with Rule 424(b) under the Securities Act. The Company will promptly advise the Representatives (i) when the Prospectus, and any supplement thereto, shall have been filed (if required) with the Commission pursuant to Rule 424(b) under the Securities Act, (ii) of the filing of any amendment or supplement to the Basic Prospectus, (iii) of the filing and effectiveness of any amendment to the Registration Statement, (iv) of any request by the Commission for any amendment of the Registration Statement, or for any amendment of or supplement to the Basic Prospectus or for any additional information, (v) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement or the institution or threatening of any proceeding for that purpose and (vi) of the receipt by the Company of any notification with respect to the suspension of the qualification of the Securities for sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose. The Company will use its best efforts to prevent the issuance of any such stop order or notice of suspension of qualification and, if issued, to obtain as soon as possible the withdrawal of such stop order including, if necessary, by filing an amendment to the Registration Statement or a new registration statement and using its best efforts to have such amendment or new registration statement declared effective as soon as practicable.

     (b) To prepare a final term sheet, containing solely a description of final terms of the Securities and the offering thereof, in the form approved by the Representatives and attached as Schedule III hereto and to file such term sheet pursuant to Rule 433(d) under the Securities Act within the time required by such Rule.

     (c) If, at any time prior to the filing of the Prospectus Supplement pursuant to Rule 424(b) under the Securities Act, any event occurs as a result of which the Disclosure Package would include any 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, the Company will (i) promptly notify the Representatives so that any use of the Disclosure Package may cease until it is amended or supplemented; (ii) subject to the first clause of the first sentence of paragraph (a) of this Section 6, amend or supplement the Disclosure Package to correct such statement or omission; and (iii) supply any amendment or supplement to the Representatives in such quantities as the Representatives may reasonably request.

     (d) If, at any time when a prospectus relating to the Securities is required to be delivered under the Securities Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), or until the distribution of any Securities an Underwriter may own as principal has been

completed, any event occurs or condition exists as a result of which (i) the Registration Statement or the Prospectus as then amended or supplemented would include an untrue statement of a material fact, or omit to state any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made at such time, not misleading, or (ii) if, in the opinion of the Representatives or in the opinion of the Company, it is necessary at any time to amend or supplement the Registration Statement or the Prospectus, as then amended or supplemented, to comply with applicable law, the Company will immediately notify each Underwriter by telephone (with confirmation in writing) to suspend solicitation of offers to purchase Securities or any resale thereof and, if so notified by the Company, each Underwriter shall forthwith suspend such solici