It is an isomer of nitramide, H2N−NO2; and a formal dimer of azanone, HNO.

trans-Hyponitrous acid forms white crystals that are explosive when dry.

In aqueous solution, it is a weak acid (pKa1 = 7.21, pKa2 = 11.54),[2] and decomposes to nitrous oxide and water with a half life of 16 days at 25 °C at pH 1–3: Since this reaction is not reversible, N2O should not be considered as the anhydride of H2N2O2.

[3] Hyponitrous acid (trans) can be prepared from silver(I) hyponitrite and anhydrous HCl in ether: Spectroscopic data indicate a trans configuration for the resulting acid.

[3] It can also be synthesized from hydroxylamine and nitrous acid: In enzymology, a hyponitrite reductase is an enzyme that catalyzes the chemical reaction:[4]