UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of Earliest Event Reported): July 28, 2005

Cabot Corporation
__________________________________________
(Exact name of registrant as specified in its charter)

Delaware	1-5667	04-2271897
_____________________ (State or other jurisdiction	_____________ (Commission	______________ (I.R.S. Employer
of incorporation)	File Number)	Identification No.)
Two Seaport Lane, Suite 1300, Boston, Massachusetts		02210-2019
_________________________________ (Address of principal executive offices)		___________ (Zip Code)

Registrant’s telephone number, including area code: 617-345-0100

Not Applicable
______________________________________________
Former name or former address, if changed since last report

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[  ]  Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
[  ]  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
[  ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
[  ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 7.01 Regulation FD Disclosure.

There were a number of questions raised during the July 28, 2005 analyst teleconference with respect to carbon black feedstock costs and the manner in which prices are adjusted under our carbon black supply contracts for such costs. In the discussion, we commented on the method by which the changes in feedstock costs impact our contract prices and management believes it is useful to provide further detail regarding these adjustments. Generally, our carbon black supply contracts provide for a price adjustment on the first day of each quarter to account for changes in feedstock costs and, in some cases, changes in other relevant costs. The feedstock adjustments are based upon the average of a relevant index over a three month period. Because of the need to communicate these adjustments to our customers in a timely manner, the contracts typically provide for the adjustments to be calculated in the month preceding the quarter. Accordingly, the calculation is typically based upon the average of the three month s preceding the month in which the calculation is made. For example, the price adjustment applicable to the quarter commencing July 1 is calculated in June using the index average during the months of March, April and May.

With respect to the relevant feedstock index, the formulas use indices that approximate movements in our actual feedstock costs. The indices typically used are Platt's Gulf Coast Spot Assessment 3% Sulfur, Platt's Rotterdam 1% Sulfur and Platt's New York #6 1% Fuel Oil.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	Cabot Corporation
July 28, 2005	By:	John A. Shaw
		Name: John A. Shaw
		Title: Executive Vice President and Chief Financial Officer