Ammonium cyanide is an unstable inorganic compound with the formula NH4CN.

Ammonium cyanide is generally used in organic synthesis.

[citation needed] Being unstable, it is not shipped or sold commercially.

Ammonium cyanide is prepared by combining solutions of hydrogen cyanide and ammonia:[citation needed] It may be prepared by the reaction of calcium cyanide and ammonium carbonate:[citation needed] In dry state, ammonium cyanide is made by heating a mixture of potassium cyanide or potassium ferrocyanide with ammonium chloride and condensing the vapours into ammonium cyanide crystals:[citation needed] Ammonium cyanide decomposes to ammonia and hydrogen cyanide, often forming a black polymer of hydrogen cyanide:[1] It undergoes salt metathesis reaction in solution with a number of metal salts to form metal–cyanide complexes.

Reaction with ketones and aldehydes yield aminonitriles, as in the first step of the Strecker amino acid synthesis: Ammonium cyanide is highly toxic.