A high capacity Li2MnSiO4 (LMS)/C nanocomposite has been prepared by glucose assisted sol–gel method with in situ carbon coating. X-ray diffraction (XRD) measurements confirm the formation of orthorhombic structure with Pmn21 space group. Field emission scanning electron microscopy (FESEM) shows that the LMS/C powders consist of uniformly distributed nanoparticles with size in the range of 20–50 nm and high-resolution transmission electron microscopy (HRTEM) confirms that amorphous carbon coat on the LMS nanocrystals. Electrochemical tests reveal that the LMS/C nanocomposite has a high initial discharge capacity of 253.4 mA h g−1 at 10 mA g−1 and superior rate capability (193.1 mA h g−1 at 160 mA g−1 and 149.9 mA h g−1 at 320 mA g−1). The improved electrochemical performance is ascribed to coated carbon and nanoparticle size, which can enhance the electronic conductivity as well as lithium-ion diffusion coefficient.