The reasons for the acceleration of the oxidation of organic substances with acids under microwave irradiation are considered. The dynamic method (under conditions of continuously increasing temperature) was used for determining the apparent activation energy (Ea). The values of Ea for the oxidation of a number of organic compounds of different classes were calculated from experimental data using the Arrhenius equation. Equal values Ea obtained for amino acid oxidation under conditions of ordinary and microwave heating are indicative of identity of oxidation mechanisms. The changes of the kinetic characteristics in the second case are probably determined by the frequency and effectiveness of collisions of interacting particles; this effect is directly associated with the action of microwave radiation. It was found that the conditions required for decomposing organic matrices can be predicted from the data on decomposition conditions for individual model compounds. © 1999 MAEe cyrillic signK "Hayκa/Interperiodica".