In this study, the application of mesoporous CeO2 and Pr doped CeO2 (Ce-Pr-O) as photocatalysts for the degradation of Rhodamine B (RhB) from aqueous solution was investigated. Mesoporous CeO2 and Ce-Pr-O were prepared using SBA-15 as template. The resultant samples were characterized by XRD, N2 adsorption-desorption, Raman, UV-vis, TEM, FT-IR, and XPS techniques. The characterization results show that the synthesized Ce-Pr-O has a 2D hexagonal structure, similar to that of the template, and possesses numerous oxygen vacancies. It is worth mentioning that the visible light adsorption intensity of Ce-Pr-O is much higher than that of mesoporous ceria and bulk ceria, due to simultaneous formation of doping level and mesopores. The photodegradation of RhB illustrates that the synthesized mesoporous Ce-Pr-O, especially 45% Ce-Pr-O, performs excellent decolorization under weak daylight irradiation. Furthermore, a novel photodegradation mechanism was proposed based on the adsorption of H2O2 over the oxygen vacancy. (C) 2014 Elsevier B.V. All rights reserved.