In its hydrous form, Na4Fe(CN)6·H2O (sodium ferrocyanide decahydrate), it is sometimes known as yellow prussiate of soda.

It is a yellow crystalline solid that is soluble in water and insoluble in alcohol.

Despite the presence of the cyanide ligands, sodium ferrocyanide has low toxicity (acceptable daily intake 0–0.025 mg/kg body weight[2]).

[3] However, like all ferrocyanide salt solutions, addition of an acid or exposure to UV light can result in the production of hydrogen cyanide gas, which is extremely toxic.

[7] Sodium ferrocyanide is produced industrially from hydrogen cyanide, ferrous chloride, and calcium hydroxide, the combination of which affords Ca2[Fe(CN)6]·11H2O.