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DIFF Subgroup
C01B 3/042

Decomposition of water (by electrolysis of water C25B1/04)

Introduced: January 2026

Title

Titles differ between systems:

IPC: Decomposition of water

CPC: Decomposition of water (by electrolysis of water C25B1/04)

Full Title

Full titles differ between systems:

IPC:

Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen > Production of hydrogen; Production of gaseous mixtures containing hydrogen > by decomposition of inorganic compounds > Decomposition of water

CPC:

Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen (production of water-gas or synthesis gas from solid carbonaceous material C10J) > Production of hydrogen; Production of gaseous mixtures containing hydrogen > by decomposition of inorganic compounds (reversible storage of hydrogen C01B3/0018) > Decomposition of water (by electrolysis of water C25B1/04)

Of 2 combined children, 1 exist in both systems.

1 codes are CPC-only extensions.

IPC defines codes here since 2026.

Child Classifications

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  • C01B 3/045 CPC only CPC only
  • C01B 3/046 using catalysts since 2026 IPC+CPC Available in IPC and CPC

Top Applicants

Top Applicants (IPC)

Class C01,2013–2023, worldwide · Source: EPO PATSTAT

  1. CHINESE ACADEMY OF SCIENCES 5,794
  2. SINOPEC (CHINA PETROCHEMICAL CORPORATION) 3,286
  3. LG CHEM KR 2,689
  4. BASF (BADISCHE ANILIN & SODA FABRIK) DE 1,669
  5. CENTRAL SOUTH UNIVERSITY 1,531
  6. KMUST (KUNMING UNIVERSITY OF SCIENCE AND TECHNOLOGY) 1,252
  7. SUMITOMO METAL MINING COMPANY JP 1,073
  8. ZHEJIANG UNIVERSITY 1,061
  9. PANASONIC INTELLECTUAL PROPERTY JP 1,058
  10. PANASONIC INTELLECTUAL PROPERTY 1,038

Top Applicants (CPC)

Class C01,2013–2023, worldwide · Source: EPO PATSTAT

  1. CHINESE ACADEMY OF SCIENCES 4,293
  2. LG CHEM KR 3,317
  3. BASF (BADISCHE ANILIN & SODA FABRIK) DE 2,219
  4. SINOPEC (CHINA PETROCHEMICAL CORPORATION) 2,154
  5. OMYA INTERNATIONAL CH 1,524
  6. PANASONIC INTELLECTUAL PROPERTY JP 1,362
  7. SAUDI ARABIAN OIL COMPANY SA 1,298
  8. SUMITOMO METAL MINING COMPANY JP 1,286
  9. CENTRAL SOUTH UNIVERSITY 1,243
  10. L'AIR LIQUIDE SOCIETE ANONYME POUR L'ETUDE ET L'EXPLOITATION DES PROCEDES GEORGES CLAUDE FR 1,238