Abstract <p>The radiolysis of the extractant <i>N</i>¹,<i>N</i>³-dimethyl-<i>N</i>¹,<i>N</i>³-dibutyltetradecylmalonamide and its 30% solution in <i>n</i>-tridecane under the action of 3-MeV electrons has been studied. The key radiolytic processes are fragmentation of the extractant molecules. The scission at the bonds in the β-position relative to the carbonyl group, N–Me, N–Bu, C–C₁₄H₂₉, and C–C(O), is predominant. The C–C(O) bond is the weakest, and its cleavage gave more than half of all the extractant degradation products. The observed yield of extractant degradation in solution is almost one and a half times higher than that in the undiluted state. At the same time, the yield of diluent degradation decreased in the solution. The observed effects indicated partial physical and chemical protection of the diluent by the dissolved extractant.</p>