Angeli's salt, sodium trioxodinitrate, is the inorganic compound with the formula Na2[N2O3].

In research, this salt is used as a source of the metastable nitroxyl (HNO), which is a signalling molecule in nature.

As first reported by Angelo Angeli in 1896, the salt is prepared by combining hydroxylamine and an organic nitrate, as a source of nitronium (NO+2):[2][3] The structure of the hydrate has been confirmed by X-ray crystallography.

The negative charge is on the oxygen atoms at opposite ends of the molecule.

[4] Reaction of Angeli's salt with secondary amines in the presence of a proton source results in extrusion of N2 via isodiazenes as proposed intermediates.