In this study, a simple sol-gel method was used for the synthesis of a core-shell structure of SiO2@alpha-Fe2O3 nanocomposites for employment as a visible light photocatalyst. It was observed that Ag nanoparticles about 20 nm in size were successfully deposited on the surface of the SiO2@alpha-Fe2O3 nanocomposites. The photocatalytic activity of the Ag-SiO2@alpha-Fe2O3 nanocomposites catalyst was investigated by observing the degradation of methylene blue (MB) dye in a photo-Fenton process. The results showed that the Ag nanoparticles acted as centers for photo induced electron transfer. The catalytic activity in the SiO2@alpha-Fe2O3 nanocomposites were enhanced due to the plasmoni c effect of Ag metal under visible light irradiation. The addition of H2O2 played an important role, generating more OH radicals which improved the photo-Fenton catalytic activity, resulting in quicker degradation of the MB dye using the Ag-SiO2@alpha-Fe2O3 nanocomposite catalyst. (C) 2017 Elsevier B.V. All rights reserved.