A cheap and rapid supercritical hydrothermal method has been adopted for the synthesis of Li2FeSiO4 cathode materials for the application in lithium ion battery. The as-synthesized Li2FeSiO4 particles at 380°C exhibited rod like morphology with 20–80nm in diameter and 500nm–1μm in length characterized by transmission electron microscopy (TEM). The Li2FeSiO4 material is systematically characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TG), scanning transmission electron microscopy (STEM) and energy dispersive X-ray (EDX). The electrochemical measurements were carried out after coating of Li2FeSiO4 particles with different weight percentage of conductive carbon. The discharge capacity of as-synthesized rod like Li2FeSiO4 with 30wt% conductive carbon coating exhibited 177mAhg−1 for the first cycle, which is more than that of as-synthesized and 20wt% conductive carbon coated rod like Li2FeSiO4 particles. The obtained discharge capacity is the highest for this material without high temperature heat treatment, which indicating that rod like morphology with diameter 20–80nm could be more active during electrochemical reactions.