Surface of mesostructured silica (SBA-15) was modified by immobilizing Fe3O4. This modified-nanosized mesoporous silica Fe3O4@SBA-15 was characterized by FTIR, XRD, BET and SEM. A comparison of the photoefficiency of Fe3O4@SBA-15 toward photodegradation of malachite green (MG) was investigated in a photocatalytic reactor using UV lamp as a light source. The effect of various experimental parameters on the degradation performance of the process was evaluated by examining catalyst dosage, initial dye concentration and pH of the dye solution in the presence of Fe3O4@SBA-15 as photocatalyst. It was found that the photocatalyst exhibited significantly high catalytic stability, and the activity loss is negligible after five MG degradation cycles. (C) 2013 Elsevier B. V. All rights reserved.