Two-solvent method was employed to prepare ZnO-CuO nanoparticles embedded in mesoporous silica SBA-15 ((ZnO-CuO)/SBA-15). The as-obtained (ZnO-CuO)/SBA-15 nanocomposites were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, N-2 adsorption porosimetry, and diffusive reflective UV-vis spectroscopy. The photocatalytic activity of (ZnO-CuO)/SBA-15 nanocomposites toward methylene orange was investigated under simulated solar light irradiation, and the measurement results indicated that (ZnO-CuO)/SBA-15 nanocomposites exhibit higher photodegradation activity toward methylene orange than commercial TiO2 P-25. The photocatalytic activity of (ZnO-CuO)/SBA-15 nanocomposites were found to be dependent on both the adsorption ability of the nanocomposites and the loading dosage of ZnO-CuO nanoparticles in SBA-15. The optimal loading dosage of ZnO-CuO nanoparticles was determined. Too high or too low loading will lower the photodegradation ability of (ZnO-CuO)/SBA-15 nanocomposites. (C) 2014 Elsevier Ltd. All rights reserved.