Magnetic CoFe2O4/graphene nanocomposites were prepared in this study by a simple hydrothermal process. The structures of these nanocomposites were investigated subsequently and the photocatalytic activities of the nanocomposites were then studied by degrading methylene blue dye. The results showed that the CoFe2O4 nanoparticles were loaded on the surface of the graphene sheets. It was also found that the photocatalytic degradation efficiency of the prepared nanocomposites improved remarkably compared with the neat CoFe2O4 salt. Significantly, these nanocomposites could be repeatedly used for several times without losing catalytic activity, indicating the nanocomposites had high photocatalytic stability. The study provides a new and effective approach to degrade dyestuff in wastewater. (C) 2015 Elsevier B.V. All rights reserved.