A high performance Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by the microwave-assisted hydrothermal method followed by a post annealing process. The synchrotron X-ray diffraction analysis results confirmed that single-phase Li3V2(PO4)3 with monoclinic structure was obtained. Scanning electron microscope and transmission electron microscope images revealed that the as-prepared Li3V2(PO4)3 was composed of nanowires and microsized particles. Electrochemical results demonstrated that the Li3V2(PO4)3 electrode measured at 10 C after 500 cycles can deliver discharge capacities of 85.4 mAh g−1 and 103.4 mAh g−1, with a capacity retention of 99.3% and 95.9%, in the voltage ranges of 3.0–4.3 V and 3.0–4.8 V, respectively, indicating good cycling stability. Furthermore, the electrochemical performance of Li3V2(PO4)3 in ionic liquid electrolytes between 3.0 V and 4.8 V was also measured.