Nickel(II) cyanide is the inorganic compound with a chemical formula Ni(CN)<sub>2</sub>. The trihydrate is a gray-green solid that is insoluble in most solvents including water, while the anhydrous form is a yellow solid.
Addition of two equivalents of sodium or potassium cyanide to a solution of nickel(II) ions in aqueous solution leads to the precipitation of nickel(II) cyanide trihydrate. On heating the trihydrate to 140 ðC, this hydrate converts to anhydrous nickel(II) cyanide.
Nickel(II) cyanide dissolves in potassium cyanide solution to produce a yellowish solution containing potassium tetracyanonickelate:
Nickel(II) cyanide will react with dimethylglyoxime (dmgH<sub>2</sub>) and produce hydrogen cyanide: