This study reports on the preparation of LiFePO4/C composite materials prepared by the hydrothermal and sol-gel processes for comparison. The synthesis condition on the hydrothermal process was performed at 170 degrees C for 19 h. The polystyrene (PS) polymer was used as a carbon source; the PS was added at a range of 0-5 wt.%. The temperature of the post-thermal process was set at 750-850 degrees C. The citric acid (denoted as CA) was used as the reducing agent and the carbon source in the sol-gel process. The temperatures of the sintering process were set at a range of 650-850 degrees C. The optimal sintering temperature was at 850 degrees C for 12 h in the hydrothermal process; the optimal carbon residue content was approximately 3.20 wt.%. It was revealed that the highest discharge capacity of LiFePO4/C composites by the hydrothermal process at 0.1 C is 163 mAh g(-1). The optimal sintering temperature was found to be at 750 degrees C for the sol-gel process. The highest carbon content was approximately 11.94 wt.% as the molar ratio of CA is 1.0. The highest discharge capacity of LiFePO4/C composites by the sol-gel process at 0.1 C was approximately 130.35 mAh g(-1). (C) 2012 Elsevier Ltd. All rights reserved.