Olivine LiFePO4 cathode materials were synthesized by hydrothermal reaction, and coated by carbon black. The powders were characterized by the X-ray diffraction. LiFePO4/Li cells were characterized electrochemically by charge/discharge experiments and ac impedance spectroscopy. The result showed the discharge capacity of LiFePO4/Li cell was 133 mAh/g at the first cycle, and 128 mAh/g at the 30th cycle, respectively.