Zirconia modified by Samarium/Europium, RE/ZrO2 (RE = Sm, Eu), composite oxide nano-materials have been successfully synthesized by improved sol-gel method. Characterization results show that X-ray diffraction (XRD) peaks of products gradually shift to the lower angle with the increase of rare earth which implies that the lattice distances of RE/ZrO2 nano-materials are gradually enlarged. Moreover, the molar ratios between zirconium and rare earth are consistent with the chemical formula and both of them are uniformly distributed in samples. Optical properties indicate that defect structures and electron configurations of RE/ZrO2 (RE = Sm, Eu) with single phase determine their absorption properties on visible light. Photocatalytic experiments indicate Zr0.8Sm0.2O2-delta nano-crystals have excellent visible-light-responsive photocatalytic activities on Methylene blue and Rhodamine B which results from the special defect structure, suitable electronic configuration, and larger specific surface area. It follows that Zr0.8Sm0.2O2-delta nano-crystals are new visible-light-responsive photocatalysts which can be applied in dye wastewater treatment and environmental protection in the future. (c) 2013 Elsevier Ltd. All rights reserved.