A CoS2/graphene nanoarchitecture was synthesized by a facile one-step hydrothermal route using graphite oxide, thioacetamide, and CoCl2·6H2O as the starting materials. The growth of CoS2 and the reduction of the graphite oxide occur simultaneously. CoS2 nanocrystals with a size of 100−150nm are uniformly anchored on the both sides of the graphene nanosheets, forming a unique CoS2/graphene hybrid nanostructure. The electrochemical tests showed that the nanocomposite exhibits obviously enhanced Li-storage properties compared with bare CoS2. The improvement in electrochemical properties could be attributed to the formation of two-dimensional conductive networks, homogeneous dispersion and immobilization of CoS2 nanoparticles, and the enhanced wetting of active material with the electrolyte by in situ introduced graphene nanosheets.