Cobalt(II) cyanide is the inorganic compound with the formula Co(CN)2.

It is coordination polymer that has attracted intermittent attention over many years in the area of inorganic synthesis and homogeneous catalysis.

Cobalt(II) cyanide has been used as a precursor to dicobalt octacarbonyl.

[2] The trihydrate salt is obtained as a reddish-brown precipitate by adding two equivalents of potassium cyanide to a cobalt salt solution:[3] With excess cyanide, the red brown dicyanide dissolves to give pentacyanocobaltate.

It forms hydrates and other inclusion complexes by having substances diffuse into the cavities that do not contain the cobalt atoms.