This study analyzed the photodegradation of the herbicide amitrole (AMT) in water by advanced oxidation processes (AOPs) based on ultraviolet (UV) radiation (UV, UV/H2O2, UV/Fe2+/H2O2, UV/K2S2O8, and UV/Na2CO3) and examined the influence of the initial concentration of radical generators, the solution pH, and the chemical composition of the water. The values of AMT reaction rate constants with HO center dot, SO4 center dot- and CO3 center dot-/HCO3 center dot radicals obtained at pH 7 were 5.85 +/- 0.25 x 10(8) M-1 s(-1), 3.77 +/- 0.17 x 108 M-1 s(-1), and 1.37 +/- 0.12 x 10(6) M-1 s(-1), respectively. The AMT degradation rate constant in the absence of radical generators (0.013 +/- 0.001 min(-1)) was considerably increased by their addition, yielding values of 0.037 +/- 0.005, 0.059 +/- 0.009, or 0.024 +/- 0.002 min(-1) with only 0.15 x 10(-3) mol L-1 H2O2, K2S2O8, or Na2CO3, respectively. In all cases, these constants increased with greater amounts of reagent, reaching values of 0.309 +/- 0.032, 0.748 +/- 0.091, and 0.043 +/- 0.004 min(-1), respectively, with the addition of 3.47 x 10(-3) mol L-1 of the corresponding radical generator. The percentage of total organic carbon removal showed the same trend as the AMT degradation rate, reaching 86.8% with the addition of 3.47 x 10(-3) mol L-1 H2O2 and increasing to 99.0% when 0.04 x 10(-3) mol L-1 Fe2+ was added to the system. We analyzed the effectiveness of three systems (UV/H2O2, UV/K2S2O8, and UV/Na2CO3) for AMT photodegradation in different types of water (ultrapure, tap, and treated urban wastewaters), verifying their high effectiveness, especially UV/K2S2O8. The high efficacy of these systems is related to the generation of both SO4 center dot- and HO center dot radicals and the greater selectivity of SO4 center dot- radical in its reaction with AMT. (C) 2015 Elsevier B.V. All rights reserved.