Molekula
Sodium thiosulfate anhydrous
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 1999 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Sodium thiosulfate anhydrous is an inorganic compound widely used as a reducing agent, in photography for fixing developed films, and in water treatment to neutralize chlorine. It also serves in medical applications for cyanide poisoning antidotes and as a laboratory reagent for iodine titration. This chemical has the CAS number 7772-98-7, with the molecular formula Na2O3S2 and a molecular weight of 158.11. It is stable at ambient storage conditions and carries no signal word for hazard classification.
Molekula supplies Sodium thiosulfate anhydrous in 100 g, 500 g and 1 kg packs, from £24.00 inc. VAT. It is in stock for same-day dispatch. Every batch ships with a certificate of analysis, and safety data sheets are available in 5 languages. Larger quantities, up to multi-tonne, are quoted on request.
Example image for illustration only. Other packaging and pack sizes are available.
Often bought together
Pricing & pack sizes
In stock — same-day dispatch
These pack sizes aren't a limit. Molekula manufactures, sources and repacks to order — if you need 500 kg and only see 1 kg listed, . We quote from grams to multi-tonne.
Need a different size? Add the nearest pack and change the size in your basket — we price it at the same rate per unit.
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100 g — £20.00 per pack ex VAT · £24.00 inc. VAT
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500 g — £24.80 per pack ex VAT · £29.76 inc. VAT
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1 kg — £42.00 per pack ex VAT · £50.40 inc. VAT
Need a different quantity or pack?
Tell us how much you need and when — drums, IBCs, sacks or a one-off bulk lot. We'll manufacture or source it and come back with a price.
Prices exclude VAT/sales tax and shipping.
Specifications
| Property | Value |
|---|---|
| Appearance | Colourless to white micro-crystalline |
| Heavy metals | ≤ 0.002% |
| Identification | Conforms to reference |
| pH | 6.5 - 9.5 |
| Water insoluble matter | ≤ 0.1% |
| Iron (Fe) | ≤ 0.005% |
| Sulfite | ≤ 0.5% |
| Active agent content as Na2S2O3 | ≥ 97% |
| Sulphate and Sulphite content as SO4 | ≤0.8% |
| Earth alkali elements as calcium | ≤0.2% |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | Ambient |
| Acidity | Neutral |
Literature values
Published physical properties of the substance, not batch specifications.
| Property | Value |
|---|---|
| Appearance | Powder |
| Melting Point | 48.5 °C |
| Refractive Index | 1.489 |
Source: PubChem CID 24477 (HSDB, ICSC)
Identification
| Property | Value |
|---|---|
| SKU | 43109159 |
| CAS Number | 7772-98-7 |
| IUPAC Name | disodium;dioxido-oxo-sulfanylidene-lambda6-sulfane |
| EC Number | 231-867-5 |
| Molecular Formula | Na2O3S2 |
| Molecular Weight | 158.11 |
| Exact Mass | 157.9084 |
| SMILES | [O-]S(=O)(=S)[O-].[Na+].[Na+] |
| InChIKey | AKHNMLFCWUSKQB-UHFFFAOYSA-L |
| InChI | InChI=1S/2Na.H2O3S2/c;;1-5(2,3)4/h;;(H2,1,2,3,4)/q2*+1;/p-2 |
| PubChem CID | 24477 |
| REACH Code | Y113 |
| TSCA Listed | Yes |
| HTS Code | 28323010 |
| Tariff Code | 2832100000 |
Safety & GHS
Precautionary statements
- P280 Wear protective gloves/protective clothing/eye protection/face protection
Documents
Safety Data Sheets (SDS)
Available in English, French, German, Italian, Spanish.
Certificate of Analysis (CoA) by batch
Enter a lot or batch number to retrieve the CoA for that specific batch. We can generate one from spec data if no PDF is on file.
Quality certificates
Molekula Group is certified to ISO 9001:2015 (quality) and ISO 14001:2015 (environmental management), audited by a UKAS-accredited body. Both certificates are valid to 17 May 2028.
Synonyms
- Chlorine Control
- Chlorine Cure
- Disodium thiosulfate
- Hypo
- Sodium oxide sulfide (Na2S2O3)
- SODIUM THIOSULFATE
- Sodium thiosulfate (Na2S2O3)
- Sodium thiosulphate
- Sodium thiosulphate (Na2S2O3)
- Thiosulfuric acid, disodium salt
Frequently asked questions
What is sodium thiosulfate anhydrous commonly used for?
Sodium thiosulfate anhydrous is primarily used in photography as a fixing agent, in water treatment for detoxifying chlorine, and in chemical synthesis as a reducing agent.
What is the chemical formula and molecular weight of sodium thiosulfate anhydrous?
The chemical formula is Na₂S₂O₃, and the molecular weight is 158.11 g/mol.
How should sodium thiosulfate anhydrous be stored?
Store in a cool, dry place at ambient temperature, away from moisture and incompatible substances.
What grades of sodium thiosulfate anhydrous does Molekula supply?
Molekula supplies sodium thiosulfate anhydrous to a specification that includes an active agent content as Na2S2O3 of at least 97%, heavy metals of no more than 0.002%, iron of no more than 0.005%, water insoluble matter of no more than 0.1% and a pH of 6.5 to 9.5.
Can Molekula supply sodium thiosulfate anhydrous in bulk quantities?
Yes, we offer bulk quantities of sodium thiosulfate anhydrous, with flexible packaging options based on customer requirements.
What documentation comes with an order of sodium thiosulfate anhydrous?
Each order includes a Certificate of Analysis (CoA), Material Safety Data Sheet (MSDS), and a packing list.
Where can I buy Sodium thiosulfate anhydrous?
Directly from Molekula, which lists Sodium thiosulfate anhydrous in 100 g, 500 g and 1 kg packs from £24.00 inc. VAT, with a certificate of analysis for every batch. Larger quantities are quoted on request. Molekula's offices: United Kingdom, France, Spain, Germany, Italy, United States and China.
Ready to order or need a custom pack?
Tell us the product, grade, and quantity — Molekula usually responds within one working day with pricing and lead time.