Thiosulfate Information



Other Names

Thiosulphate; Thiosulfate Ion

Chemical Formula


CAS Number

14383 – 50 – 7

Industry Uses

Bleaching; Chemical Laboratories

Health Risks


Thiosulfate MSDS

What is Thiosulfate?

Thiosulfate is an excellent reducing agent. It is used primarily as a chlorine-removing agent, or antichlor, in various chemical processes. In industry it is used for the bleaching of pulp, paper, and textiles. Thiosulfate Ions are commonly bonded with Sodium to form hyposulfite or sodium thiosulfate. Hyposulfite is used to fix black and white negatives and prints in photography. Ammonium thiosulfate is a fixing salt. In acidic conditions, thiosulfate causes rapid corrosion of metals. It causes pitting corrosion to steel and stainless steel. Thiosulfate occurs naturally only in a very rare mineral, sidpietersite.

Thiosulfate Exposure and Health Risks

Thiosulfate may cause skin and eye irritation if contacted directly. Prolonged or repeated contact can cause dermatitis. Inhalation of thiosulfate can cause respiratory distress and irritation of the entire respiratory tract. Ingestion of thiosulfate may be harmful.


There are no explicit restrictions or regulations from the EPA regarding Thiosulfate concentration in water. 

Measuring Thiosulfate

Dissolved Thiosulfate concentration in water can be measured in units of parts per million (ppm). We carry instrumental kits from CHEMetrics that determine thiosulfate levels in water. All of our thiosulfate products can be viewed HERE.

The Thiosulfate Kits are designed to accurately measure thiosulfate levels in water using the Iodometric Method.

The K-9705 Thiosulfate Titrets Kit is used to measure thiosulfate levels from 5-50ppm.

Contact us for help choosing the right monitor for your application