Sodium thiosulfate is an inorganic sodium salt composed of sodium and thiosulfate ions in a 2:1 ratio. It has a role as an antidote to cyanide poisoning, a nephroprotective agent and an antifungal drug. It contains a thiosulfate(2-).

1. Photography: Main component of fixer, dissolves unexposed silver halides.
2. Chemical industry: Reducing agent, dechlorinating agent, electroplating complexing agent, dye auxiliary.
3. Environmental protection: Dechlorination of drinking water / wastewater, cyanide antidote.
4. Medicine: First aid for cyanide poisoning, antidote for metal poisoning, treatment of skin diseases.
5. Aquaculture: Water quality improvement, detoxification, pH adjustment.