Using a hydrothermal method, a composite of Co3O4 supported on graphene nanosheets (Co3O4-GNs) was prepared. Morphological characterization revealed that the Co3O4 nanoparticles with a size of 100–200 nm were dispersed randomly on the planes of GNs. As an anode material for lithium-ion batteries, Co3O4-GNs composite shows an improved electrochemical performance in the initial coulombic efficiency (57%), reversible capacity (657 mAh g−1 after 100 cycles at a current of 50 mA g−1) and cycling stability, which is much better than bare Co3O4 and GNs electrodes. The superior results can be attributed to high surface area and good electronic conductivity of GNs.