FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person *   Kalkstein Hobart 2. Date of Event Requiring Statement (Month/Day/Year) 04/07/2016 3. Issuer Name and Ticker or Trading Symbol CABOT CORP [CBT] (Last) (First) (Middle) C/O CABOT CORPORATION, TWO SEAPORT LANE, SUITE 1300 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Senior Vice President 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) BOSTON, MA 02210 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5) Common Stock 18,152.902 (1) D   Common Stock 14,130 I Held jointly by the Hobart C. Kalkstein Revocable Trust and Andrea H. Kalkstein Revocable Trust Common Stock 5,818.0574 I (2) Through the Trustee for the Corporation's 401(k) Plan

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (Right to Buy)	  (3)	05/06/2019	Common Stock	16,300	$ 16.9	D	Â
Employee Stock Option (Right to Buy)	  (4)	11/13/2024	Common Stock	4,017	$ 46.03	D	Â
Employee Stock Option (Right to Buy)	  (5)	11/11/2025	Common Stock	5,763	$ 39.54	D	Â
Phantom Stock	  (6)	  (6)	Common Stock	1,980.476	$ (6)	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Kalkstein Hobart C/O CABOT CORPORATION TWO SEAPORT LANE, SUITE 1300 BOSTON, MA 02210	Â	Â	  Senior Vice President	Â

Signatures

By: Karen Kalita, pursuant to a power of attorney from Hobart C. Kalkstein		04/11/2016
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Includes 1,259 performance based units earned on the basis of the Corporation's performance in fiscal year 2014 and 2015 (which remain subject to time-based vesting) and 7,140 units subject to time-based vesting.
(2)	Reflects retirement plan contributions by the Corporation.
(3)	The option vested over a three year period as follows: 30% on May 7, 2010, 30% on May 7, 2011 and 40% on May 7, 2012.
(4)	The option vests over a three year period as follows: 30% on November 14, 2015, 30% on November 14, 2016 and 40% on November 14, 2017.
(5)	The option vests over a three year period as follows: 30% on November 12, 2016, 30% on November 12, 2017 and 40% on November 12, 2018.
(6)	Each share of phantom stock is the economic equivalent of one share of Cabot Corporation common stock. The shares of phantom stock will be settled in shares of Cabot Corporation common stock upon termination of his employment with Cabot Corporation.

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