Deuterium labeled tributyl phosphates were synthesized and their solutions in n-dodecane have been investigated for γ radiolytic degradation up to an absorbed dose of 2,000 kGy from a ⁶⁰Co source. The performance was compared with undeuterated TBP. Radiolysis extent and pattern of formation of major degradation products, viz. dibutyl hydrogen phosphate and monobutyl dihydrogen phosphate were found to be very similar from deuterated or undeuterated samples. Extraction behavior for UO₂ ²⁺ and Pu(IV) was studied after the radiolysis, and the results showed similarity in extraction /stripping behavior for all labeled or unlabeled TBP samples. The isotope effect (k_H/k_D) observed is minimal in this γ-radiolytic degradation study.