Cyanogen is the chemical compound with the formula (CN)₂. The simplest carbon nitride, it is a colorless and highly toxic gas with a pungent odor. The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups – analogous to diatomic halogen molecules, such as Cl₂, but far less oxidizing. The two cyano groups are bonded together at their carbon atoms: N≡C‒C≡N, although other isomers have been detected. The name is also used for the CN radical, and hence is used for compounds such as cyanogen bromide (NCBr) (but see also Cyano radical.)

Cyanogen is the anhydride of oxamide:

H₂NC(O)C(O)NH₂ → NCCN + 2 H₂O

although oxamide is manufactured from cyanogen by hydrolysis:

NCCN + 2 H₂O → H₂NC(O)C(O)NH₂