LiFePO4 as a cathode material for rechargeable lithium batteries was prepared by hydrothermal process at 170°C under inert atmosphere. The starting materials were LiOH, FeSO4, and (NH4)2HPO4. The particle size of the obtained LiFePO4 was 0.5μm. The electrochemical properties of LiFePO4 were characterized in a mixed solvent of ethylene carbonate and diethyl carbonate (1:1 in volume) containing 1.0moldm−3 LiClO4. The hydrothermally synthesized LiFePO4 exhibited a discharge capacity of 130mAhg−1, which was smaller than theoretical capacity (170mAhg−1). The annealing of LiFePO4 at 400°C in argon atmosphere was effective in increasing the discharge capacity. The discharge capacity of the annealed LiFePO4 was 150mAhg−1.