Sodium thiosulfate

INS 539CAS 7772-98-7

Used as a preservative — Codex also lists it as antioxidant, sequestrant.

Sodium thiosulfate is an antioxidant and sequestrant, and is used to remove residual chlorine and iodine from processing water.

Where it is and isn’t permitted

Status of Sodium thiosulfate by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationPermitted21 CFR 184.1807retrieved 2026-09-07
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

59 food categories

highest permitted level 1,000 mg/kg

Show every food category
  • 04.1.1.2 Surface-treated fresh fruit — 30 mg/kg
  • 04.1.2.1 Frozen fruit — 500 mg/kg
  • 04.1.2.10 Fermented fruit products — 100 mg/kg
  • 04.1.2.11 Fruit fillings for pastries — 100 mg/kg
  • 04.1.2.2 Dried fruit — 1,000 mg/kg
  • 04.1.2.3 Fruit in vinegar, oil, or brine — 100 mg/kg
  • 04.1.2.5 — 100 mg/kg
  • 04.1.2.6 Fruit-based spreads (e.g. chutney) excluding products of food category — 100 mg/kg
  • 04.1.2.7 Candied fruit — 100 mg/kg
  • 04.1.2.8 Fruit preparations, including pulp, purees, fruit toppings and coconut milk — 100 mg/kg
  • 04.1.2.9 Fruit-based desserts, incl. fruit-flavoured water-based desserts — 100 mg/kg
  • 04.2.1.3 Peeled, cut or shredded fresh vegetables, (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweeds and nuts and seeds — 50 mg/kg
  • 04.2.2.1 Frozen vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweeds and nuts and seeds — 50 mg/kg
  • 04.2.2.2 Dried vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweeds, and nuts and seeds — 500 mg/kg
  • 04.2.2.3 Vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), and seaweeds in vinegar, oil, brine, or soybean sauce — 100 mg/kg
  • 04.2.2.4 Canned or bottled (pasteurized) or retort pouch vegetables (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), and seaweeds — 50 mg/kg
  • 04.2.2.5 Vegetable (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweed, and nut and seed purees and spreads (e.g. peanut butter) — 500 mg/kg
  • 04.2.2.6 Vegetable (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera), seaweed, and nut and seed pulps and preparations (e.g. vegetable desserts and sauces, candied vegetables) other than food category 04.2.2.5 — 300 mg/kg
  • 04.2.2.7 Fermented vegetable (including mushrooms and fungi, roots and tubers, pulses and legumes, and aloe vera) and seaweed products, excluding fermented soybean products of food categories 06.8.6, 06.8.7, 12.9.1, — 500 mg/kg
  • 06.2.1 Flours — 200 mg/kg
  • 06.2.2 Starches — 50 mg/kg
  • 06.4.3 Pre-cooked pastas and noodles and like products — 20 mg/kg
  • 06.8.2 Soybean-based beverage film — 200 mg/kg
  • 07.2 Fine bakery wares (sweet, salty, savoury) and mixes — 50 mg/kg
  • 09.1.2 Fresh molluscs, crustaceans, and echinoderms — 100 mg/kg
  • 09.2.1 Frozen fish, fish fillets, and fish products, including molluscs, crustaceans, and echinoderms — 100 mg/kg
  • 09.2.4.2 Cooked molluscs, crustaceans, and echinoderms — 150 mg/kg
  • 09.2.5 Smoked, dried, fermented, and/or salted fish and fish products, including molluscs, crustaceans, and echinoderms — 30 mg/kg
  • 09.4 Fully preserved, including canned or fermented fish and fish products, including molluscs, crustaceans, and echinoderms — 150 mg/kg
  • 11.1.1 White sugar, dextrose anhydrous, dextrose monohydrate, fructose — 15 mg/kg
  • 11.1.2 Powdered sugar, powdered dextrose — 15 mg/kg
  • 11.1.3 Soft white sugar, soft brown sugar, glucose syrup, dried glucose syrup, raw cane sugar — 20 mg/kg
  • 11.1.5 Plantation or mill white sugar — 70 mg/kg
  • 11.2 Brown sugar excluding products of food category 11.1.3 — 40 mg/kg
  • 11.3 Sugar solutions and syrups, also (partially) inverted, including treacle and molasses, excluding products of food category 1.1.1.3 — 70 mg/kg
  • 11.4 Other sugars and syrups (e.g. xylose, maple syrup, sugar toppings) — 40 mg/kg
  • 12.2.1 Herbs and spices — 150 mg/kg
  • 12.2.2 Seasonings and condiments — 200 mg/kg
  • 12.3 Vinegars — 100 mg/kg
  • 12.4 Mustards — 250 mg/kg
  • 12.6 Sauces and like products — 300 mg/kg
  • 12.9.1 Fermented soybean paste (e.g. miso) — 30 mg/kg
  • 14.1.2.1 Fruit juice — 50 mg/kg
  • 14.1.2.2 Vegetable juice — 50 mg/kg
  • 14.1.2.3 Concentrates for fruit juice — 50 mg/kg
  • 14.1.2.4 Concentrates for vegetable juice — 50 mg/kg
  • 14.1.3.1 Fruit nectar — 50 mg/kg
  • 14.1.3.2 Vegetable nectar — 50 mg/kg
  • 14.1.3.3 Concentrates for fruit nectar — 50 mg/kg
  • 14.1.3.4 Concentrates for vegetable nectar — 50 mg/kg
  • 14.1.4 Water-based flavoured drinks, including "sport," “energy,” or "electrolyte" drinks and particulated drinks — 70 mg/kg
  • 14.2.1 Beer and malt beverages — 50 mg/kg
  • 14.2.2 Cider and perry — 200 mg/kg
  • 14.2.3 Grape wines — 350 mg/kg
  • 14.2.4 Wines (other than grape) — 200 mg/kg
  • 14.2.5 Mead — 200 mg/kg
  • 14.2.6 Distilled spirituous beverages containing more than 15% alcohol — 200 mg/kg
  • 14.2.7 Aromatized alcoholic beverages (e.g. beer, wine and spirituous cooler-type beverages, low-alcoholic refreshers) — 250 mg/kg
  • 15.1 Snacks - potato, cereal, flour or starch based (from roots and tubers, pulses and legumes) — 50 mg/kg
CXS 192-1995 Table One, INS 539and 58 further provisionsretrieved 2026-09-07

What it is made from

Produced by reacting sodium sulfite with sulfur. It is the same compound photographers used as fixer.

  • Vegan
  • Vegetarian
CAS registry number
7772-98-7
InChIKey
AKHNMLFCWUSKQB-UHFFFAOYSA-L
PubChem
CID 24477

Every name it appears under

62 recorded names. A label may use any of them.

INS number

  • 539

CAS registry number

  • 7772-98-7

As it appears in regulation

  • Sodium thiosulfate

Other names

  • Ametox
  • Analytical Volumetric Solution Sodium Thiosulfate Solution 0.1M
  • anhydrous sodium thiosulfate
  • Chlorine Control
  • Chlorine Cure
  • Cyanide Antidote Package
  • Declor-It
  • disodium sulfurothioate
  • Disodium thiosulfate
  • DISODIUM THIOSULPHATE
  • disodium;dioxido-oxo-sulfanylidene-lambda6-sulfane
  • European Pharmacopoeia Reagent 0.1M Sodium Thiosulphate-Naturally short expiry
  • HSDB 592
  • Hypo
  • Hypo (VAN)
  • Hypo alcohol, in ethanol
  • Ins no.539
  • Ins-539
  • L0IYT1O31N
  • Natrii thiosulfas
  • PEDMARK
  • Reagecon Sodium Thiosulfate 0.05M Solution according to Chinese Pharmacopoeia (ChP)
  • Reagecon Sodium Thiosulfate 0.1M according to Japanese Pharmacopoeia
  • S-Hydril
  • Sodium hyposulfite
  • Sodium Nitrite and Sodium Thiosulfate
  • Sodium oxide sulfide
  • Sodium oxide sulfide (Na2S2O3)
  • Sodium subsulfite
  • sodium thio-sulfate
  • sodium thiosulfat
  • Sodium thiosulfate
  • Sodium thiosulfate (Na2S2O3)
  • Sodium thiosulfate solution (2 g/dL in deionized water)
  • Sodium thiosulfate solution 0.1mol/L (N/10)
  • Sodium thiosulfate, >=99.99% trace metals basis
  • Sodium thiosulfate, anhydrous
  • Sodium thiosulfate, anhydrous, Trace metals grade 99.99%
  • Sodium thiosulfate, AR, >=98%
  • Sodium thiosulfate, LR, >=97%
  • Sodium thiosulfate, p.a., 98.0%
  • Sodium thiosulfate, purum p.a., anhydrous, >=98.0% (RT)
  • Sodium thiosulfate, ReagentPlus(R), 99%
  • Sodium thiosulfate, SAJ first grade, >=90.0%
  • Sodium thiosulfate, Vetec(TM) reagent grade, 99%
  • Sodium thiosulphate
  • Sodium thiosulphate (Na2S2O3)
  • Sodium thiosulphate, anhydrous
  • sodiumthiosulfate
  • Sodothiol
  • Sodothiol; Sulfactol; Sulfothiorine
  • sulfothiorine
  • Thiosulfate, Sodium, Pentahydrate
  • Thiosulfuric acid (H2S2O3), disodium salt
  • Thiosulfuric acid (H2S2O3), sodium salt (1:2)
  • Thiosulfuric acid, disodium salt
  • Thiosulfuric acid, disodium salt, pentahydrate
  • USP Solution Sodium Thiosulfate 0.100 Normal (N/10) Conforms to USP

Systematic names

  • Disodium;dioxido-oxo-sulfanylidene-lambda6-sulfane

Hazard reference values

No reference value for this substance in the sources we hold.

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.

Sources for this page

  • ecfr retrieved 2026-09-07
  • gsfa retrieved 2026-09-07

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable:/api/v1/additives/sodium-thiosulfate.json