In this study, the roles of TaON and Ta3N5 in the degradation of atrazine by the visible-Fenton-like system were examined in detail. The TaON and Ta3N5 samples prepared by the nitridation of Ta2O5 and characterized by XRD, DRS, BET and PL analyses. The results showed that the TaON sample had weaker absorption in the visible region but higher specific surface area than the Ta3N5 sample. The degradation rate of atrazine in visible-TaON-Fenton-like system was 2.64 times than that in visible-Ta3N5-Fenton-like system. Both Fe2+ and H2O2 could be reduced by e(CB) (electrons in the conduction band) in TaON or Ta3N5, while atrazine could not be oxidized by h(VB) (holes in the valance band). center dot OH is the active species for the degradation of atrazine in visible-TaON/Ta3N5-Fenton-like systems. Majority of center dot OH originated from Fenton reaction. After Fe3+ was reduced by e(CB) to Fe2+, Fe2+ reacted quickly with H2O2 to generate center dot OH. In addition, by capturing e(CB), a little of H2O2 was reduced to yield center dot OH, which contributed a small fraction of atrazine degradation. Based on the experimental results, the roles of TaON and Ta3N5 in the visible-Fenton-like system were proposed. And the higher photocatalytic activity of TaON than Ta3N5 was suggested to be due to the higher separation efficiency of electrons and holes, which may be related to the larger specific surface area. (C) 2013 Elsevier B.V. All rights reserved.