A novel photocatalyst of LaMn1 - xCoxO3/graphene composites had been synthesized by sol-gel process assisted with chelating effect of citric acid. The structure, morphology and valence state of prepared samples were characterized by thermogravimetry-differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra and UV-vis absorbance spectra. It was found that LaMnO3 perovskite phase was successfully processed which anchored on the surface of graphene sheets, and doping Co did not change the perovskite structure. The UV-vis photocatalytic activity of the photocatalysts was evaluated by the degradation of diamine green B. The results indicated that the photocatalytic activity of composites depend strongly on the doping content of Co. LaMn1 - xCoxO3/graphene composites prepared with x = 0.15 had the greatest photocatalytic activity, and it displayed good stability during the photocatalytic and recycling processes. (C) 2014 Elsevier B.V. All rights reserved.