Exhibit 21

Subsidiaries of Cabot Corporation (as of September 30, 2017)

Subsidiary	State/Jurisdiction of Incorporation
Cabot Argentina S.A.I.C.	Argentina
Cabot Australasia Pty. Ltd.	Australia
Cabot Australasia Investments Pty. Ltd.	Australia
Cabot Plastics Belgium S.A.	Belgium
Cabot Performance Materials Belgium S.P.R.L.	Belgium
N.V. Norit Belgium	Belgium
Cabot (Bermuda) Ltd.	Bermuda
Cabot Brasil Industria e Comércio Ltda.	Brazil
Tantalum Mining Corporation of Canada Limited	Manitoba, Canada
Coltan Mines Limited	Manitoba, Canada
Cabot Finance N.B. LP	New Brunswick, Canada
Cabot Canada Ltd.	Ontario, Canada
Cabot Norit Canada Inc.	New Brunswick, Canada
Cabot Plastics Hong Kong Limited	China
Shanghai Cabot Chemical Company Ltd.	China
Cabot Trading (Shanghai) Company Ltd.	China
Cabot (China) Limited	China
Cabot Bluestar Chemical (Jiangxi) Co., Ltd.	China
Cabot Chemical (Tianjin) Co., Ltd.	China
Cabot Performance Products (Tianjin) Co., Ltd.	China
Cabot Risun Chemical (Xingtai) Co., Ltd.	China
Norit China Limited	China
Cabot HengYeCheng Performance Materials (Inner-Mongolia) Company Limited	China
Cabot Colombiana S.A.	Colombia
CS Cabot spol, s.r.o.	Czech Republic
Cabot Czech Holding Company s.r.o.	Czech Republic
Cabot France S.A.S.	France
Cabot Carbone S.A.S.	France
Cabot GmbH	Germany
Cabot Holdings I GmbH	Germany
Cabot Holdings II GmbH	Germany
Cabot Aerogel GmbH	Germany

Subsidiary	State/Jurisdiction of Incorporation
Cabot India Limited	India
P.T. Cabot Indonesia	Indonesia
Cabot Italiana S.p.A.	Italy
Cabot Performance Materials Italy S.r.l	Italy
Cabot Norit Italia S.p.A.	Italy
Aizu Holdings G.K.	Japan
Cabot Asia Kumiai	Japan
Cabot Japan K.K.	Japan
Cabot Supermetals K.K.	Japan
Cabot Norit Japan Co. Ltd.	Japan
Cabot Korea Y.H.	Korea
SIA Cabot Latvia	Latvia
Cabot Luxembourg Holdings S.a.r.l.	Luxembourg
Cabot Luxembourg Investments S.a.r.l.	Luxembourg
Cabot Luxembourg Finance S.a.r.l.	Luxembourg
Cabot Luxembourg TC S.a.r.l.	Luxembourg
Cabot NHUMO Holdings I S.a.r.l.	Luxembourg
Cabot Asia Sdn. Bhd.	Malaysia
Cabot Elastomer Composites Sdn Bhd.	Malaysia
Cabot Materials Research Sdn Bhd.	Malaysia
Cabot (Malaysia) Sdn. Bhd.	Malaysia
CMHC, Inc.	Mauritius
Cabot Specialty Fluids (Singapore) Pte. Ltd.	Singapore
Cabot Norit Singapore Pte. Ltd.	Singapore
Cabot Specialty Fluids Mexico S. de R. L. de C.V.	Mexico
Cabot NHUMO Holding S.A.P.I., de C.V.	Mexico
Cabot Specialty Chemicals Mexico S.A.P.I. de C.V. (formerly NHUMO, S.A.P.I. de C.V.)	Mexico
Altamira Carbon, S.A. de C.V.	Mexico
Mexico Reinforcement Materials, S.A.P.I. de C.V.	Mexico
Cabot S.A.	Spain
Cabot International GmbH	Switzerland
Cabot Switzerland GmbH	Switzerland
Cabot B.V.	The Netherlands
Cabot Finance B.V.	The Netherlands
Cabot Activated Carbon B.V.	The Netherlands
Cabot Performance Materials Netherlands B.V.	The Netherlands
Norit Holding B.V.	The Netherlands
Norit International N.V.	The Netherlands

Subsidiary	State/Jurisdiction of Incorporation
Norit Real Estate B.V.	The Netherlands
Norit EAPA Holding B.V.	The Netherlands
Cabot Norit Nederland B.V.	The Netherlands
Cabot Norit Technology B.V.	The Netherlands
Black Rose Investments Limited	British Virgin Islands
Dragón Verde Investments Limited	British Virgin Islands
AHB Investments Limited	British Virgin Islands
HDF Investments Limited	British Virgin Islands
Ramaai Holdings Limited	British Virgin Islands
Cabot Performance Products FZE	Dubai, United Arab Emirates
Botsel Limited	United Kingdom (England)
Cabot Carbon Limited	United Kingdom (England)
Cabot G.B. Limited	United Kingdom (England)
Cabot Plastics Limited	United Kingdom (England)
Cabot U.K. Limited	United Kingdom (England)
Cabot UK Holdings Limited	United Kingdom (England)
Cabot UK Holdings II Limited	United Kingdom (England)
Cabot UK Holdings III Limited	United Kingdom (England)
Cabot Performance Materials UK Limited	United Kingdom (England)
Cabot Specialty Fluids Limited	United Kingdom (Scotland)
Cabot Specialty Fluids North Sea Limited	United Kingdom (Scotland)
Norit (UK) Holding Limited	United Kingdom (Scotland)
Cabot Norit (UK) Limited	United Kingdom (Scotland)
Purton Carbons Limited	United Kingdom (Scotland)
Anglo Dutch Water Carbons Limited	United Kingdom (England)
Cabot Activated Carbon Holdings UK Limited	United Kingdom (England)
Cabot Activated Carbon UK Limited	United Kingdom (England)
BCB Company	Delaware, United States
Cabot Asia Investments Corporation	Delaware, United States
Cabot Ceramics, Inc.	Delaware, United States
Cabot Corporation Foundation, Inc.	Massachusetts, United States
Cabot CSC LLC	Delaware, United States
Cabot Europe Limited	Delaware, United States
Cabot Holdings LLC	Delaware, United States
Cabot Insurance Co. Ltd. (Vermont)	Vermont, United States
Cabot International Limited	Delaware, United States
Cabot International Capital Corporation	Delaware, United States
Cabot International Services Corporation	Massachusetts, United States

Subsidiary	State/Jurisdiction of Incorporation
Cabot Specialty Chemicals, Inc.	Delaware, United States
Cabot Specialty Fluids, Inc.	Delaware, United States
CDE Company	Delaware, United States
CDE II LLC	Delaware, United States
Energy Transport Limited	Delaware, United States
Cabot US Finance LLC	Delaware, United States
Cabot US Investments LLC	Delaware, United States
Kawecki Chemicals, Inc.	Delaware, United States
Norit Americas Holding Inc.	Delaware, United States
Cabot Norit Americas Inc.	Georgia, United States
Marshall Mine LLC	Delaware, United States
Cabot Activated Carbon LLC	Delaware, United States
Representaciones 1, 2 y 3 C.A.	Venezuela
Valores Ramaai C.A.	Venezuela