Sodium thiosulphate is the neutral salt of thiosulphuric acid.

Sodium thiosulphate pentahydrate in the configuration of monocline crystals of various particle sizes and an active agent content of at least 99% Na2S2O3 ⋅ 5 H2O

Special mention should be given to the following from the wide range of applications of sodium thiosulphate:
• usage in photographic chemicals for producing fixing baths;
• removal of halogens from waste water and waste gas and from bleached textiles, paper and cellulose;
• raw material in the chemical industry;
• as an ingredient for chrome tanning in the dual bath process for the production of special leather types;
• in the cosmetic industry;
• usage as a laboratory chemical.