Hydrogen peroxide
CAS 7722-84-1 · EC 231-765-0 · H2O2
Also known as peroxide
Hazard data are for the pure substance; household 3% solutions are classified as mixtures.
Handle chemistry safely
Wear gloves and eye protection, work with good ventilation, and read the supplier’s safety data sheet before use. Hazard information here is a summary, not a replacement for it. Dispose of all photographic chemistry correctly, in line with local laws and your local authority’s guidance. Never mix waste solutions, and check the supplier’s safety data sheet before disposing of anything.
Hazards
Official EU classification (harmonised under CLP Annex VI).
Signal word: Danger
Oxidising · Harmful or irritant · Corrosive
- H271 May cause fire or explosion; strong oxidiser.
- H332 Harmful if inhaled.
- H302 Harmful if swallowed.
- H314 Causes severe skin burns and eye damage.
UK and EU rules
- UK Poisons Act 1972: REGULATED explosives precursor above 12% w/w – an EPP licence is needed for members of the public to acquire/possess above that concentration (GOV.UK list of chemicals, 3 July 2026)
Photographic uses
- hypo eliminator (Kodak HE-1, 3% solution)
- cyanotype intensification
Sources
- ECHA CHEM substance record: Hydrogen peroxide (100.028.878)
- ECHA CHEM – C&L Inventory (harmonised CLP Annex VI and notified classifications) and legal obligations (chem.echa.europa.eu APIs: /api-cnl-inventory/harmonized|industry, /api-obligation-substance/v1)
- Supplying explosives precursors and poison substances: list of chemicals (supplying-explosives-precursors/list-of-chemicals (updated 3 July 2026))
Checked October 2026.