The influence of thermal and gamma radiation effects on the characteristics of the thermal explosion of mixtures of tributyl phosphate (TBP) and nitric acid was studied. The products of sequential radiolysis and pyrolysis of TBP were determined to have little effect on the thermal stability of mixtures of TBP and nitric acid. The onset temperatures of exothermic processes leading to a thermal explosion were slightly decreased only by the absorbed dose of 2 MGy. The thermal stabilities of solutions of TBP in n-dodecane and diluent C-13, consisting of a mixture of saturated hydrocarbons, were investigated. The experimental results indicate that the irradiation decreased the onset temperature of the exothermic processes in mixtures of nitric acid with TBP solutions in a hydrocarbon diluent; the onset temperature decreased by 5°C to 7°C for n-dodecane and by 9°C to 13°C for C-13, as compared to unirradiated extractants.