Safety data sheet reference · CAS 7772-98-7
Sodium thiosulfate SDS
also: sodium thiosulfate MSDS · safety data sheet · Na2S2O3 · CAS 7772-98-7 · hypo
Official PDF from supplier
This page is a reference, not the legal document.
CAS number
7772-98-7
Molecular formula
Na2S2O3
No harmonised EU classification
Sodium thiosulfate has no entry in CLP Annex VI — there is no harmonised EU-wide classification for it. That is not evidence of safety. Suppliers remain obliged to self-classify it under CLP, and workplace hazards (dust, asphyxiation, thermal) can exist without a harmonised entry. Always obtain the supplier's SDS for the product you actually use.
§ 03 · Composition and identifiers
Sodium thiosulfate structure
Sodium thiosulfate is an ionic compound — there is no discrete Na2S2O3 molecule. The diagram shows the ions the crystal lattice is built from.
Ions of sodium thiosulfate · Na2S2O3
Identifiers from PubChem (NIH, public domain). Structure diagram drawn with RDKit from the SMILES string.
MSDS vs SDS
Sodium thiosulfate MSDS vs SDS: is there a difference?
MSDS (Material Safety Data Sheet) is the older name for the same document. In the US, OSHA's Hazard Communication Standard (2012) adopted the GHS-standardised 16-section Safety Data Sheet; in the EU the format is set by REACH Annex II. So a "sodium thiosulfate MSDS" and a "sodium thiosulfate SDS" refer to the same document — today it is issued as an SDS. Full breakdown of the differences →
Compliance hub
From classification to SDS
The classification above corresponds to Section 2 of a Safety Data Sheet. Learn how a compliant 16-section SDS is structured and authored →
GHS label maker
Build the label for sodium thiosulfate
Pictograms, signal word and H-statements combined into a compliant label layout →
§ 16 · Sources
- Classification: Regulation (EC) No 1272/2008 (CLP), Annex VI
- Transport: UN ADR 2025 (UNECE), Table A
- Reactivity: NOAA CAMEO Chemicals reactive-group matrix (public domain)
- Physical properties: CAMEO Chemicals (NOAA, public domain) — per-value source references stored in the database
- Substance data: PubChem · ECHA
Reference aid only. This page summarises the harmonised EU classification and computed storage guidance — it is not a Safety Data Sheet and does not replace one. Always verify hazards, handling and storage against the supplier's SDS (sections 7 and 10) and local regulations before use. Page updated 2026-08-11.
Frequently asked questions about sodium thiosulfate
Is an MSDS the same as an SDS?
In practice, yes. MSDS (Material Safety Data Sheet) is the older name for the same document. In the US, OSHA's Hazard Communication Standard (2012) adopted the GHS-standardised 16-section Safety Data Sheet; in the EU the SDS format is set by REACH Annex II. A document you find labelled "sodium thiosulfate MSDS" is today issued as an SDS.
Where can I download an official sodium thiosulfate SDS PDF?
From your own supplier — an SDS is issued per product and supplier, so the correct PDF for an inspection is the one matching the product you actually purchased. The supplier links on this page lead to the official SDS libraries of major distributors.