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Water Electrolysis — Patent Landscape 2000–2024

Comprehensive patent landscape analysis of water electrolysis and hydrogen production by electrolysis — 25,611 patent families filed at 73 offices worldwide, from established electrochemical players to a new wave of Chinese universities driving the green hydrogen transition.

Data: EPO PATSTAT Global, Autumn 2025 Period: 2000–2024 Created: March 2026 Author: mtc.berlin
25,611
Patent Families
2000–2024
73
Patent Offices
worldwide
86×
Growth Factor
57 → 4,929 families/yr
41.7%
Grant Rate
10,687 granted families
16.7%
Co-Filing Rate
4,285 co-filed families

Executive Summary

Key findings from the water electrolysis patent landscape, 2000–2024.

Explosive Growth

Annual patent family filings grew from 57 in 2000 to 4,929 in 2023 — an 86-fold increase. The inflection point came around 2016, when annual filings more than doubled from 413 (2015) to 871 (2016). Growth accelerated further after 2020, with 2021–2023 accounting for 44% of all families.

China Dominates

68% of all families (17,441) include a filing at the Chinese patent office (CNIPA). China grew from just 189 families in 2000–2009 to 13,303 in 2020–2024. The next largest offices — WO (5,602), US (5,106), KR (3,453), EP (3,422) — lag far behind.

Universities Lead

Since approximately 2017–2018, universities (primarily Chinese) have filed more patent families per year than companies. Overall, universities account for 37.6% of families vs. 35.9% for companies. By 2024, university filings (2,012) exceeded company filings (1,159) by a factor of 1.7×.

Electrode Research Leads

Electrodes (C25B 11/) are the largest technology sub-area with 12,233 families, followed by cell construction (10,342) and operation/control (7,231). These component-level areas reflect the field's focus on improving efficiency and durability of electrolyzer systems.

Robert Bosch GmbH leads with 290 patent families, followed by Dalian Institute of Chemical Physics (213) and Huaneng Clean Energy Research Institute (204). Notable newcomers since 2020 include Huaneng (21.8× growth ratio), China Petroleum & Chemical Corp (12.3×), and Tsinghua University (11.1×).

Filing Trend 2000–2024

Annual patent family filings by earliest filing year per DOCDB family.

Filing activity grew from 57 families in 2000 to 4,929 in 2023 — an 86-fold increase. The inflection point is clearly visible around 2016, when annual filings more than doubled from 413 to 871. The slight decrease in 2024 (4,400) is expected due to the ~18-month publication delay in PATSTAT Autumn 2025.

* 2023–2024: Data may be incomplete due to the ~18-month publication delay (PATSTAT Autumn 2025 Edition).

Data table: Filing Trend 2000–2024
Year Families YoY Change
200057
200165+14.0%
200256−13.8%
200392+64.3%
200488−4.3%
2005106+20.5%
2006102−3.8%
2007178+74.5%
2008202+13.5%
2009196−3.0%
2010258+31.6%
2011264+2.3%
2012301+14.0%
2013370+22.9%
2014388+4.9%
2015413+6.4%
2016871+110.9%
20171,023+17.5%
20181,482+44.9%
20191,618+9.2%
20201,864+15.2%
20212,826+51.6%
20223,462+22.5%
20234,929+42.4%*
20244,400−10.7%*

Top Applicants

Top 15 applicants by number of DOCDB patent families (2000–2024).

Robert Bosch GmbH (DE) leads with 290 families, followed by Dalian Institute of Chemical Physics (213) and Huaneng Clean Energy Research Institute (204). Of the top 15, 9 are Chinese universities or research institutes (shown in blue), reflecting the strong academic push in China's hydrogen strategy. European players include Bosch, CEA (France), and Siemens Energy (rank 19, 119 families).

Data table: Top 15 Applicants
Applicant Country Families Active
Robert Bosch GmbHDE2902010–2025
Dalian Institute of Chemical PhysicsCN2132015–2024
Huaneng Clean Energy Research InstituteCN2042015–2024
Shaanxi Univ. of Science and TechnologyCN1922017–2024
Matsushita / PanasonicJP1802004–2025
Zhejiang UniversityCN1602016–2024
Beijing Univ. of Chemical TechnologyCN1522016–2024
Qingdao Univ. of Science & TechnologyCN1492016–2024
CEA Energies AlternativesFR1462005–2025
KAISTKR1452004–2024
ToshibaJP1422008–2025
Tianjin UniversityCN1412016–2024
Jilin UniversityCN1382016–2024
South China Univ. of TechnologyCN1362016–2024
Tsinghua UniversityCN1332017–2024

Technology Sub-Areas

CPC-based breakdown of technology focus within C25B. Families can carry multiple CPC codes — totals are non-exclusive and exceed the total family count.

Electrodes (12,233 families) and cell construction (10,342) are the largest component-level sub-areas, reflecting the field's focus on improving electrolyzer efficiency and durability. Operation and control systems (7,231) rank third, indicating growing interest in system integration. Photoelectrolysis (1,777) and steam electrolysis / SOEC (759) remain niche but are growing.

Patent families can be assigned to multiple technology areas. Chart totals exceed the total family count of 25,611.

Data table: Technology Sub-Areas
Technology Area Families
Water Electrolysis (C25B 1/04)22,562
Electrodes (C25B 11/)12,233
Cell Construction (C25B 9/)10,342
Operation / Control (C25B 15/)7,231
Other C25B3,083
H2/O2 General (C25B 1/02)2,178
Membranes / Diaphragms (C25B 13/)1,838
Photoelectrolysis (C25B 1/55)1,777
Steam Electrolysis / SOEC (C25B 1/042)759
Mixed H2+O2 Gas (C25B 1/044)375

Geographic Analysis

Filing distribution across patent offices and geographic shift over time.

China accounts for 68% of all families (17,441), followed by international PCT filings at WIPO (5,602) and the US (5,106). The European Patent Office (3,422) and Korea (3,453) are nearly tied. Filing at 73 offices worldwide indicates strong global interest in hydrogen electrolysis technology protection.

Geographic Shift by Period

Families per office across four time periods, showing China's dramatic rise.

Office 2000–2009 2010–2015 2016–2019 2020–2024
CN 189 563 3,395 13,303
WO 461 1,020 1,056 3,104
US 645 1,084 1,153 2,257
EP 300 614 738 1,787
KR 408 483 796 1,767
JP 265 541 614 1,180
DE 129 182 203 654

A family may have filings at multiple offices. Row values are non-exclusive across offices.

Sector Analysis

Applicant type breakdown and sector trends over time. Families with multiple applicants from different sectors appear in each sector — totals are non-exclusive.

Universities account for 37.6% of families (9,604), surpassing companies at 35.9% (9,174). This is unusual for most technology areas and reflects the strong role of Chinese academic institutions in hydrogen research. The "Other / Unknown" category (27.4%) includes entities with unclassified PATSTAT sector codes — many of these are likely Chinese state-owned enterprises or research institutes.

Sector Trend Over Time

Annual families by sector, showing the university crossover point around 2017–2018.

The university-company crossover occurred around 2017–2018. Before 2013, individual inventors were the second-largest group — a pattern consistent with early-stage technology fields. Since 2016, institutional filing (universities + companies) has dominated, coinciding with national hydrogen strategies in China and Europe.

* 2023–2024: Data may be incomplete due to ~18-month publication delay. Individual filings in 2024 (23) appear artificially low.

Data table: Sector Trend 2000–2024
Year Company University Individual Other
20003623110
20056686713
20101612521532
2015219999773
2016365280178135
2017426419115164
2018504730143222
2019512878119261
2020648924105419
20219491,0921181,099
20221,1271,168861,575
20231,7071,683862,088
20241,1592,012231,657

Growth Dynamics

Established players (30+ total families, 5+ in 2016–2019) ranked by growth ratio from 2016–2019 to 2020–2024.

Huaneng Clean Energy shows the most dramatic acceleration with a 21.8× growth ratio (9 → 196 families). China Petroleum & Chemical Corp (12.3×) and Tsinghua University (11.1×) follow. European players Robert Bosch (9.8×) and Siemens Energy (6.9×) also show strong growth, confirming that this is a global trend — not only driven by China.

Data table: Growth Dynamics
Applicant 2016–2019 2020–2024 Total Growth Ratio
Huaneng Clean Energy Research Institute919620621.8×
China Petroleum & Chemical Corp7869312.3×
Tsinghua University1112213311.1×
Ningbo Inst. Materials Technology5505510.0×
Toyota549669.8×
Robert Bosch GmbH252442909.8×
Soochow University545559.0×
Linde GmbH649558.2×
Nantong University539447.8×
Mitsubishi Heavy Industries536437.2×
Siemens Energy Global151031196.9×
Hyundai Motor Company534396.8×
Jiangsu Univ. Sci. & Tech.640466.7×
Kunming Univ. Sci. & Tech.1067776.7×
Hyundai Motor Co1067846.7×

Collaboration Network

Top co-applicant pairs by shared DOCDB patent families. 16.7% of all families (4,285) have multiple applicants.

Partner A Partner B Shared Families
Huaneng Clean Energy Research Inst. Huaneng Group Technology Innovation Center 104
Sichuan Huaneng Jialingjiang Hydro. Sichuan Huaneng Kangding Hydro. 86
Huaneng Group Tech. Innovation Center Sichuan Huaneng Taipingyi Hydro. 86
Huaneng Clean Energy Research Inst. Sichuan Huaneng Kangding Hydro. 86
Huaneng Mingtai Electric Power Sichuan Huaneng Taipingyi Hydro. 86
Sichuan Huaneng Baoxinghe Hydro. Sichuan Huaneng Dongxiguan Hydro. 86

The collaboration network is dominated by the Huaneng Group conglomerate. The top 15 co-applicant pairs are all Huaneng subsidiaries filing jointly — Huaneng Clean Energy Research Institute, Huaneng Group Technology Innovation Center, and various Sichuan Huaneng hydropower subsidiaries sharing 86–104 families each. This reflects a corporate filing strategy where multiple group entities are listed as co-applicants, rather than independent collaboration.

Interpretation Note

  • The Huaneng dominance in co-filings may obscure genuine inter-organizational collaborations.
  • A deeper analysis excluding intra-group co-filings would be needed to map independent collaboration patterns.
  • University-industry pairs (e.g., CEA + industrial partners) appear further down the ranking.

Grant Rate Analysis

Grant rates by patent office for the 2000–2020 filing cohort. Recent filings excluded to allow for examination pendency (3–5 years).

Japan (70.8%) and Korea (68.2%) show the highest grant rates, followed by the US (62.6%) and China (58.3%). The EPO grant rate of 49.4% reflects its more rigorous examination process. Germany's low rate (17.3%) is partly explained by families that enter the national phase via EP and are not separately examined at DPMA. The WO rate (3.5%) is expected — PCT applications are not granted by WIPO but enter national phases.

Grant rates for filings after 2020 are artificially low due to examination pendency and are excluded from this analysis.

Data table: Grant Rates by Office (2000–2020 cohort)
Office Total Families Granted Families Grant Rate
CN5,3853,13858.3%
US3,0821,92962.6%
WO2,750953.5%
KR1,9531,33268.2%
EP1,82790349.4%
JP1,5491,09670.8%
DE5659817.3%

Application Domains

Co-occurring IPC subclasses reveal where water electrolysis technology intersects with other fields. Families carry multiple IPC codes — totals are non-exclusive.

Catalysis (B01J, 3,811 families) and fuel cells/batteries (H01M, 3,780) are the most frequent co-occurring domains, reflecting the close link between electrolyzer electrode materials and catalytic/electrochemical research. Non-metallic elements (C01B, 2,968) covers hydrogen and oxygen compounds. The presence of power networks (H02J, 1,141) and water treatment (C02F, 1,685) shows electrolysis extending into grid integration and water purification.

Excluding C25B (the core electrolysis subclass, 24,931 families). IPC codes are aggregated across all family members.

Data table: Top 10 Co-occurring IPC Subclasses
IPC Subclass Description Families
B01JChemical or physical processes, catalysis3,811
H01MFuel cells, batteries, direct energy conversion3,780
C01BNon-metallic elements and compounds2,968
B82YNanostructures — specific uses1,696
C02FTreatment of water, waste water, sewage1,685
B01DSeparation processes1,436
H02JElectric power networks, circuit arrangements1,141
C01GCompounds containing metals959
C25DElectrolytic or electrophoretic production947
C07CAcyclic or carbocyclic compounds811

Methodology

Search strategy, data sources, and known limitations.

Search Strategy

CPC-based classification search using three core codes:

  • C25B 1/02 — Electrolytic production of hydrogen or oxygen (general)
  • C25B 1/04 — Hydrogen by electrolysis of water (core code, includes C25B 1/042 for SOEC)
  • C25B 1/55 — Photoelectrolysis

Union of all three codes = 25,611 distinct DOCDB families.

Family Counting

DOCDB family grouping is used throughout to avoid double-counting the same invention across jurisdictions. One DOCDB family = one invention, regardless of how many national applications exist.

Data Source

EPO PATSTAT Global, Autumn 2025 Edition, accessed via Google Cloud BigQuery (project: patstat-mtc, dataset: patstat). Analysis date: March 2026.

Multi-Assignment Note

Patent families can be assigned to multiple CPC codes, IPC subclasses, and applicant sectors. Charts showing technology sub-areas, application domains, or sector breakdowns have non-exclusive totals that exceed the total family count.

Scope Limitations

  • Design patents and utility models are excluded (ipr_type = 'PI' — patent applications only).
  • Title-only families (~5.6%, estimated 1,432 families) not carrying the scope CPC codes are excluded.
  • Broader hydrogen production methods (reforming, biomass gasification) are not covered.
  • 2023–2024 data is incomplete due to the ~18-month publication delay in PATSTAT Autumn 2025.
  • PATSTAT's han_name harmonization may merge or split entities incorrectly in edge cases.
  • The "Other / Unknown" sector (27.4%) includes entities without PATSTAT sector classification — likely Chinese SOEs and research institutes.

Acknowledgement

This analysis was inspired by the work of Riccardo Priore at Area Science Park (Centro Patlib, Trieste, Italy), who developed an interactive patent applicant exploration tool for the electrolyzer domain using EPO's Technology Intelligence Platform (TIP). His original analysis covered ~18,800 patent families. This report reproduces and extends his research question using PATSTAT Global on BigQuery.

Stack

PATSTAT BigQuery + patstat-mcp (custom MCP server) + Claude AI for analysis and visualization. All queries are reproducible.

Glossary — Patent Terms Explained
Patent Family (DOCDB)
A group of patent applications that protect the same invention across different countries. Counted once to avoid double-counting.
EP / WO / DE / US / CN / JP / KR
Patent office codes: EP = European Patent Office, WO = International (PCT), DE = Germany (DPMA), US = United States, CN = China (CNIPA), JP = Japan (JPO), KR = Korea (KIPO).
CPC (Cooperative Patent Classification)
A classification system jointly maintained by EPO and USPTO, more granular than IPC. Used as the primary search layer in this report.
IPC (International Patent Classification)
A hierarchical system for classifying patents by technology area, maintained by WIPO. Used for application domain analysis.
SOEC (Solid Oxide Electrolyzer Cell)
A type of electrolyzer that uses a solid oxide ceramic as the electrolyte, operating at high temperatures (600–900°C) for steam electrolysis.
PEM (Proton Exchange Membrane)
A type of electrolyzer using a polymer membrane as the electrolyte, operating at lower temperatures with fast response times.
Grant Rate
Percentage of patent applications that are ultimately granted. Rates for recent years appear low because examination takes 3–5 years.
Co-Filing / Co-Application
A patent application with more than one applicant. Indicates collaboration between organizations or joint ownership of the invention.

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