Sodium thiosulfate pentahydrate is used as an analytical reagent in laboratories. It is used in photographic processing and in gold extraction. Its alkylated derivatives, S-alkylthiosulfonates, are known as Bunte salts. It is involved in the preparation of thioglycolic acid. Furthermore, it is used to dechlorinate tap water, for removing free bromine from solutions and to check the pH of bleach solutions with liquid indicators. Other uses include tanning of leather; as an active component in hand warmers and chemical heating pads and as an anionic surfactant to aid in the dispersion of pharmaceutical preparations.
