Radiation-induced decomposition of tributyl phosphate-nitric acid as a two-component system has been studied. Degradation products, dibutylphosphoric acid (DBP) and monobutylphosphoric acid (MBP), were determined by separation-extraction method. 0.59, 0.78 and 1.38 are the G (DBP) values and 0.15, 0.17 and 0.13 are the G (MBP) values obtained for pure TBP, TBP-3M HNO3 extract and TBP-5M HNO3 extract, respectively. G (–HNO3) values are 5.19 and 6.15 for 3M HNO3 and 5M HNO3 extracts. It is shown that nitric acid plays a significant role in enhancing the decomposition of TBP.