Degradation of Acid Orange 7 (AO7) was employed to evaluate the catalytic activity of the Fe3+ doped CeO2 in the presence of H2O2. Fe3+ doping in the ceria improved the degradation of AO7 in the dark as well as under the visible light irradiation and showed the highest catalytic activity at Fe/Ce = 1/100 (FC100). XPS, Raman and EPR studies showed that Fe3+ doping in the CeO2 greatly affected the concentration of Ce3+. FC100 was found to have the highest Ce3+ concentration. Raman and EPR studies confirmed the presence of surface peroxide-like species, which was derived from the complex of the surface Ce3+ and H2O2. DMPO spin trapping EPR studies indicated that peroxide-like species played a key role during the dark-reaction, while (OH)-O-center dot radical induced the degradation of AO7 under visible irradiation. The amounts of both active species were remarkably increased in the FC100/H2O2 system than those in the CeO2/H2O2 system. (C) 2010 Elsevier B.V. All rights reserved.