Kinetics of the thermal decomposition of dinitramide (HDN) in aqueous solutions and of NH4N(NO2)(2) (ADN) and KN(NO2)(2) (KDN) in sulfuric acid, nitric acid and anhydrous acetic acid solutions was studied. The species N(NO2)(2)(-), HN(NO2)(2) and H2N(NO2)(2)(+) were established to take part in the decomposition over a wide range of the medium acidity. Kinetic regularities of their thermal decomposition were determined. The role of the decomposition of dinitramide at the initial and self-acceleration stages of the decomposition of ADN was determined. The most likely mechanism of the decomposition of dinitramide, N(NO2)(2)(-) and H2N(NO2)(2)(+) was proposed.