The Hydrogen Studies dataset
Every study in this database, as one table you can download and reuse: 2,276 papers on molecular hydrogen (348 in people), with the paper's identity, our design classification and the structured fields we have extracted. Free, under Creative Commons Attribution 4.0 International (CC BY 4.0). Regenerated from the live database every hour; this copy was generated November 4, 2026.
- Download CSV — 2,276 rows, 25 columns
- Download JSON — the same records as an array
What is in it
One row per live study: title, authors, journal, year, DOI (2,204 rows) and PubMed ID (1,976 rows) as indexed; our study-design class; whether the study was in people; sample size, duration, delivery method, hydrogen concentration, outcome direction, funding and conflict-of-interest statements where our extraction has recorded them; condition and body-system tags; country; and the paper's OpenAlex citation count with its refresh date. Fields the paper does not report are blank, never guessed.
What is not in it: abstracts (they belong to their publishers; each row links to the paper), our prose summaries, and the papers we have excluded as retracted or off topic (the methodology page gives the current count and reasons). Extraction coverage is partial and documented on the methodology page; the limits of the evidence page shows what the numbers can and cannot support.
Fields
| Column | Meaning |
|---|---|
id | Our stable numeric id for the study. |
url | The study's page on hydrogenstudies.com. |
title | The paper's title as indexed. |
authors | Authors as indexed, comma-separated. |
journal | Journal name as indexed. |
year | Publication year. |
doi | Digital Object Identifier, when known. |
pmid | PubMed ID, when known. |
study_design | Our design classification: meta_analysis, rct, controlled_trial, uncontrolled_trial, observational, case_report, review, animal, in_vitro, other, or blank when not yet classified. |
human | true when the study involved human participants. |
species_or_model | The study population label as extracted (e.g. human, rat, mouse, cells). |
sample_size | Number of participants or animals, when the paper reports it. |
duration_days | Intervention duration in days, when the paper reports it. |
delivery_method | How hydrogen was given, as extracted (e.g. water, inhaled gas, saline). |
h2_concentration | Hydrogen concentration as stated in the paper, when extracted. |
outcome_direction | Direction of the main result as recorded by our pipeline: positive, neutral, negative or mixed. |
health_conditions | Condition tags, separated by '|'. |
body_systems | Body-system tags, separated by '|'. |
country | Country of the corresponding institution, as indexed. |
funding_sources | Funding statement as extracted, when recorded (human studies so far). |
conflict_of_interest | Conflict-of-interest statement as extracted, when recorded. |
citation_count | Citations to the paper per OpenAlex, with the refresh date in citation_count_as_of. |
citation_count_as_of | Date the citation count was last refreshed (ISO 8601). |
openalex_id | OpenAlex work id, when matched. |
excluded | Always false in this export: retracted and off-topic papers are not included. |
Licence and citation
The dataset is released under Creative Commons Attribution 4.0 International (CC BY 4.0): use it for anything, including commercially, as long as you credit Hydrogen Studies and link back. The underlying papers remain their authors' and publishers'; the licence covers our compilation, classification and extracted fields.
Suggested citation: Hydrogen Studies (2026). The Hydrogen Studies dataset, version 2026-11-04. Echo Technologies LLC. https://hydrogenstudies.com/dataset. Licensed CC BY 4.0.
A persistent DOI for versioned snapshots is planned. Until then, cite the version date above; the CSV filename carries it.
How it is made
Papers enter the database from PubMed, Europe PMC and CrossRef every six hours and pass a topic screen; retracted papers are removed daily. Design classes and the structured fields are drafted by language models from the abstract or full text and checked in audits and spot checks; the outcome direction is the pipeline's reading of the main result. Full detail on the methodology page. Found an error in a row? Tell us and we fix the record, which fixes the dataset.
For the summary numbers see the state of hydrogen research.