Nitrosyl azide is a highly labile nitrogen oxide with chemical formula N₃NO.

Nitrosyl azide can be synthesized via the following reaction of sodium azide and nitrosyl chloride at low temperatures:

Below −50 °C, nitrosyl azide exists as a pale yellow solid. Above this temperature, it decomposes into nitrous oxide N₂O and molecular nitrogen N₂:^[1]

Characterization of the compound with IR and Raman spectroscopy show absorption bands that agree well with calculated values for a trans-structure.^[1][2] Quantum chemical calculations show a cis-form higher in energy by 4.2 kJ/mol and an aromatic ring form that is more stable by 205 kJ/mol. However, the cyclization to the ring form would have to surpass the 205 kJ/mol activation energy barrier require to bend the azide group, which might explain why nitrosyl azide is stable enough to be isolated at low temperature.^[1]