Degradation of aqueous 3,4-dichloroaniline (3,4-DCA) using gamma-ray irradiation was attempted in this study. The role of e(aq)(-), during the degradation process was analyzed in detail. The results demonstrated that effective degradation of aqueous 3,4-DCA using gamma-ray irradiation was realized; when the initial concentration of 3,4-DCA was 0.050 mmol L-1, and the irradiation dose was 0.4 kGy, the degradation efficiency of 3,4-DCA reached 96.2%. The degradation process of 3,4-DCA could be depicted by the pseudo first order reaction kinetics. Dechlorination was observed during the degradation process, and the concentration of detected Cl- in the treated 3,4-DCA solution increased with increasing irradiation dose. The sequence of the contribution of free radicals to the 3,4-DCA degradation was center dot OH > e(aq)(-) > center dot H. The quantum efficiency ratio of center dot OH, e(aq)(-) and center dot H for the degradation of 3,4-DCA was 1:1:4. The degradation efficiency of 3,4-DCA was accelerated by the addition of H2O2, and the appropriate addition amount was 0.05% (v/v). However, HCO3-, NO3- and NO2- (as additives) reduced the degradation efficiency of 3,4-DCA. A gas chromatograph-mass spectrometer was employed to identify the degradation intermediates, indicating that p-chloroaniline was the primary degradation intermediate with the addition of 2-propanol. (C) 2016 Elsevier B.V. All rights reserved.