Potassium ferrocyanide

E number E536INS 536CAS 13943-58-3

Used as an anticaking agent.

Potassium ferrocyanide is an anticaking agent for table salt, added in tiny amounts to stop it clumping. Despite the name it contains no free cyanide: the cyanide is locked to iron in a complex that does not release it.

Where it is and isn’t permitted

Status of Potassium ferrocyanide by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationNot listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited.
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

3 food categories

highest permitted level 20 mg/kg

Show every food category
  • 12.1.1 Salt — 14 mg/kg
  • 12.1.2 Salt substitutes — 20 mg/kg
  • 12.2.2 Seasonings and condiments — 20 mg/kg
CXS 192-1995 Table One, INS 536and 2 further provisionsretrieved 2026-09-07

What it is made from

Manufactured from hydrogen cyanide, iron salts and potassium hydroxide. The resulting complex is stable and passes through unchanged, which is why it is permitted at all.

  • Vegan
  • Vegetarian
CAS registry number
13943-58-3
InChIKey
XOGGUFAVLNCTRS-UHFFFAOYSA-N
PubChem
CID 9605257

Every name it appears under

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

E number

  • E536

INS number

  • 536

CAS registry number

  • 13943-58-3

Other names

  • E 536
  • Ferrate(4-), hexakis(cyano-kappaC)-, potassium (1:4), (OC-6-11)-
  • Ferrate(4-), hexakis(cyano-kappaC)-, tetrapotassium, (OC-6-11)-
  • Ferrate(4-a)a, hexakis(cyano-aI masculineC)a-a, potassium (1:4)a, (OC-a6-a11)a-
  • gelbes Blutlaugensalz
  • HEXACYANOFERRATE OF POTASSIUM
  • INS NO.536
  • INS-536
  • Kaliumhexazyanoferrat(II)
  • lambda6-iron(6+) ion tetrapotassium hexakis(iminomethanide)
  • OCPOWIWGGAATRP-UHFFFAOYSA-N
  • potassium (iii) ferrocyanide
  • Potassium (Oc-6-11)-Hexakis(Cyano-Kappa-C)Ferrate(4-)(4:1)
  • Potassium ferrocyanate
  • Potassium ferrocyanide
  • Potassium ferrocyanide, solution
  • potassium hexacyanidoferrate(4-)
  • potassium hexacyanidoferrate(II)
  • Potassium hexacyanoferrate
  • potassium hexacyanoferrate(4-)
  • Potassium hexacyanoferrate(II)
  • Tetrapotassium ferrocyanide
  • tetrapotassium hexacyanidoferrate
  • Tetrapotassium hexacyanoferrate
  • Tetrapotassium hexacyanoferrate(4-)
  • Tetrapotassium hexacyanoferrate(II)
  • Tetrapotassium hexakis(cyanido-kappaC)ferrate(4-)
  • tetrapotassium hexakis(cyanido-kappakappaC)ferrate(4-)
  • Tetrapotassium Hexakis(Cyano-C)Ferrate(4-)
  • tetrapotassium;iron(2+);hexacyanide
  • Yellow prussiate of potash

Systematic names

  • Potassium hexacyanoferrate(II)
  • Tetrapotassium hexacyanoferrate trihydrate; Tetrapotassium hexacyanoferrate(4-) trihydrate

Hazard reference values

Values set by assessing bodies. A body that has not set a value is not listed here.
TypeValuePopulationAssessed byOpinion
ADI0.03 mg/kg bw/dayconsumersEFSAnot identified in the dataset

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

  • 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/potassium-ferrocyanide.json