Cabot Corporation Announcement

August 3, 2006

BOSTON, Aug. 3 /PRNewswire-FirstCall/ -- Cabot Corporation (NYSE: CBT) today announced plans to withdraw its common stock from listing on the Pacific Exchange, Inc., now known as NYSE Arca, Inc. Cabot's common stock will continue to be listed on the New York Stock Exchange, its principal listing exchange, and on the Boston Stock Exchange. Cabot has decided to withdraw the listing to reduce administrative requirements and expenses.

Cabot Corporation is a global specialty chemicals and materials company headquartered in Boston, MA. Cabot's major products are carbon black, fumed silica, inkjet colorants, capacitor materials, and cesium formate drilling fluids. The website address is: http://www.cabot-corp.com.

Contact: Susannah R. Robinson

Director, Investor Relations
(617) 342-6129

SOURCE Cabot Corporation
CONTACT: Susannah R. Robinson, Director, Investor Relations, of Cabot Corporation, +1-617-342-6129