Lithium iron metasilicate, LiFeSi₂O₆, was synthesized via a hydrothermal route and was identified as the pyroxene structure with space group C2/c using the synchrotron X-ray diffraction. Galvanostatic charge and discharge tests showed that the large charge and discharge capacities were obtained for the carbon-LiFeSi₂O₆ composite prepared by planetary ball-milling. The 10 wt % carbon-LiFeSi₂O₆ composite delivered a specific discharge capacity of 174 mAh·g⁻¹ at 25°C in the voltage range from 1.5 to 4.8 V because of the enhancement of the electric conductivity. The valence state of iron was estimated by the X-ray Absorption Near Edge Structure spectra, where the oxidation states changed from charge to discharge state. The Galvanostatic Intermittent Titration measurement was applied for LiFeSi₂O₆ and carbon-LiFeSi₂O₆ composite, and then the improved Li⁺ diffusion was derived from the fully electron supply by the enhanced electric conductivity.