On July 9, 2012, Cabot Corporation (the "Company") entered into an underwriting agreement (the "Underwriting Agreement") with J.P. Morgan Securities LLC and Citigroup Global Markets Inc., as representatives of the several underwriters named in Schedule 1 thereto (collectively, the "Underwriters"), pursuant to which the Company agreed to sell, and the Underwriters agreed to purchase, upon the terms and subject to the conditions set forth therein, $250,000,000 aggregate principal amount of its 2.550% Senior Notes due 2018 (the "2018 Notes") and $350,000,000 aggregate principal amount of its 3.700% Senior Notes due 2022 (the "2022 Notes" and, together with the 2018 Notes, the "Notes").

On July 12, 2012, the Company completed the issuance and sale of the Notes. In connection with the closing of the issuance and sale of the Notes, the Company entered into a supplemental indenture (the "Second Supplemental Indenture") with U.S. Bank National Association, as trustee, relating to the Notes.

The Notes were registered on Form S-3 under the Securities Act of 1933 (Registration Statement No. 333-162021) (the "Registration Statement"). In order to furnish certain exhibits for incorporation by reference into the Registration Statement, the Company is filing the Underwriting Agreement, the Second Supplemental Indenture, the opinion of Ropes & Gray LLP relating to the validity of the Notes and the consent of KPMG Accountants N.V. as exhibits to this filing.

(d) Exhibits.

 1.1    Underwriting Agreement dated as of July 9, 2012 by and among Cabot
        Corporation and J.P. Morgan Securities LLC and Citigroup Global Markets
        Inc., as representatives of the several underwriters named in Schedule 1
        thereto.

 4.1    Second Supplemental Indenture dated as of July 12, 2012 between Cabot
        Corporation, as issuer, and U.S. Bank National Association, as Trustee,
        including the form of Global Note attached as Annex A thereto,
        supplementing the Indenture dated as of September 21, 2009.

 5.1    Opinion of Ropes & Gray LLP as to the validity of the Notes.

23.1    Consent of KPMG Accountants N.V.

23.2    Consent of Ropes & Gray LLP (included in Exhibit 5.1).