Exhibit 12.1

Cabot Corporation

Unaudited Computation of Ratios of Pro Forma Earnings to Fixed Charges and

Preferred Stock Dividends

	Pro Forma Nine Months Ended 6/30/2009			Pro Forma Fiscal Year Ended 9/30/2008
	(Dollars in millions except for ratios)
(Loss) income from continuing operations before taxes, equity in net income of affiliated companies and minority interest	$	(92	)	$	112
Add:
Fixed charges		39			59
Distributed income of affiliated companies		2			2
(Loss) earnings as adjusted	$	(51	)	$	173
Interest expense	$	32		$	50
Capitalized interest		2			3
Estimate of interest in rental expense (33%)		7			9
Fixed Charges		41			62
Preferred stock dividends:		—			—
Combined fixed charges and preferred stock dividends	$	41		$	62
Ratio of earnings to combined fixed charges and preferred stock dividends		N/A	(1)		2.8	x

(1) The earnings to fixed charge ratio is negative because of the loss. The total dollar amount of the deficiency is $92 million.