The dynamics of gas evolution during the thermal oxidation of 30% solutions of tri-n-butyl phosphate (TBP) in Isopar-M saturated with 4.3, 8.2 and 12.0 mol/L nitric acid was investigated in open vessels in the temperature range of 70°C to 150°C. The volume of the released gases has been measured. The influence of the pre-irradiation by accelerated electrons has been determined for the thermolysis and accumulation of liquid products of TBP degradation in the system TBP-Isopar-M-HNO3. The temperature borders of oxidation processes transition to autocatalytic regime have been estimated. It has been shown, that the conditions resulting in growth of autocatalytic oxidation do not exist under heating of single-phase systems in open vessels.