Hyponitrous acid is the chemical compound H2N2O2. This can be formulated as HON=NOH and is an isomer of nitramide, (H2N−NO2). It forms white crystals that are explosive when dry.
Hyponitrous acid is a weak acid (pKa1=7.21, pKa2=11.54) in aqueous solution and decomposes to N2O and water with a half-life of 16 days at 25°C at pH1–3.