In order to enhance energy density, a hybrid type pseudocapacitor/electric double layer capacitor (EDLC) was considered and its electrochemical properties were investigated. At various current densities, stable charge/discharge behaviors were observed with much higher specific capacitance values of 530 F/g compared with that of EDLC (230 F/g), by introducing Ni(OH)(2) as a cathode material. By using the modified cathode of a Ni(OH)(2)/activated carbon composite electrode, the specific capacitance was less sensitive to charge/discharge current density exhibiting stable power characteristics.