Cyanogen azide is a chemical compound with the chemical formula CN₄, or more precisely ⁻N=N⁺=N−C≡N. It is an azide compound of carbon and nitrogen. It is an oily, colourless liquid at room temperature.^[2] It is a highly explosive chemical that is soluble in most organic solvents, and normally handled in dilute solution in this form.^[2][3][4] It was first synthesised by F. D. Marsh at DuPont in the early 1960s.^[2][5] There had been earlier claims of discovering it as a crystalline solid, which were incorrect.^[6]

Cyanogen azide is a primary explosive, although it is far too unstable for practical use as an explosive and is extremely dangerous outside dilute solution.^[7][8] Its use in chemistry has been as a reagent prepared in situ for use in the synthesis of chemicals such as diaminotetrazoles, either in dilute solution or as a gas at reduced pressure.^{[9][10][11][6][12][13][14]} It can be synthesised at below room temperature from the reaction of sodium azide with either cyanogen chloride^[2] or cyanogen bromide,^[5] dissolved in a solvent such as acetonitrile; this reaction must be done with care due to the production of shock-sensitive byproducts from trace moisture.^[5][12]