A convenient chitosan-assisted hydrothermal and postannealing strategy was successfully developed to fabricate 2D ultrathin MoS2/graphene heterostructures. The resultant heterostructures were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption-desorption. It was found that the ultrathin MoS2 nanosheets were of few-layered structures (3-4 layers) and were well anchored on the large flexible graphene flakes to form heterostructures, which had more uniform mesoporosity and larger surface area than the pristine MoS2. As a result, the obtained MoS2/graphene heterostructure electrode exhibited superior electrochemical lithium-storage performances such as high reversible specific capacity (similar to 1100 mAh g(-1)), excellent cyclic stability and significantly enhanced rate capability. The prominent electrochemical performance could be attributed to the robust 2D mesoporous heterostructures composed of ultrathin few-layered MoS2 nanosheets and highly conductive graphene as well as the resultant positive synergistic effect between them. (C) 2015 Elsevier Ltd. All rights reserved.