GHS hazard statement
H261: In contact with water releases flammable gas
- H261
- Physical hazards
- Danger
H261 means “In contact with water releases flammable gas”. It is a GHS hazard statement for Substances and mixtures which in contact with water, emit flammable gases (Category 2), shown with GHS02 under the signal word “Danger”.
Hazard class and category
| Hazard class | Category | Pictogram | Signal word | UN transport class |
|---|---|---|---|---|
| Substances and mixtures which in contact with water, emit flammable gases | Category 2 |  | Danger | Div 4.3 |
| Substances and mixtures which in contact with water, emit flammable gases | Category 3 | | Warning | Div 4.3 |
What H261 means
Substances and mixtures which, in contact with water, emit flammable gases are solids or liquids that react with water to give off a flammable gas, sometimes in dangerous quantities or with enough heat to ignite it.
Contact with water, damp air or moisture can release flammable gas that may ignite spontaneously. Using water to fight a fire involving the material can make it worse.
What to do
Keep dry and in tightly closed containers, protect from moisture, do not use water to extinguish a fire unless the SDS says it is safe, and use only the extinguishing agents the SDS lists.
This is general guidance for the hazard class. The safety data sheet for your product always takes precedence.
Precautionary statements for H261
The GHS lists these precautionary statements for this hazard. Which ones appear on a label depends on the supplier's classification.
| Code | Statement |
|---|---|
| P223 | Do not allow contact with water. |
| P231+P232 | Handle and store contents under inert gas/... Protect from moisture. |
| P280 | Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/... |
| P302+P335+P334 | Brush off loose particles from skin. Immerse in cool water [or wrap in wet bandages]. |
| P370+P378 | In case of fire: Use ... to extinguish. |
| P402+P404 | Store in a dry place. Store in a closed container. |
| P501 | Dispose of contents/container to ... |
Chemicals carrying H261
No chemicals in our database are classified with H261 yet.
H261 frequently asked questions
What does H261 mean?
H261 means "In contact with water releases flammable gas". It is a GHS hazard statement in the physical hazards group, covering Substances and mixtures which in contact with water, emit flammable gases (Category 2).
Which pictogram goes with H261?
H261 is shown with GHS02 (Flame). By category: Category 2: GHS02, signal word Danger; Category 3: GHS02, signal word Warning.
What signal word goes with H261?
It depends on the category: Category 2: GHS02, signal word Danger; Category 3: GHS02, signal word Warning.
Which precautionary statements go with H261?
The GHS data lists 7 precautionary statements for H261, including P223, P231+P232, P280, P302+P335+P334, P370+P378. They cover prevention, response, storage and disposal. The full list is on this page.
Hazard statements describe the hazard of a classified substance or mixture. The classification of a specific product can differ, so use the supplier's SDS.
https://pubchem.ncbi.nlm.nih.gov/ghs/ghscode_10.txt (UN GHS Revision 10, retrieved 2026-10-12)