Abstract: This study reports a hybrid capacitor in H₂SO₄ aqueous electrolyte, which consists of polyaniline as a cathode and activated carbon as an anode. The electrochemical performance of the hybrid capacitor is characterized by cyclic voltammetry and a constant current charge/discharge test. The hybrid capacitor shows capacitor behavior with an extended operating voltage of 1.4 V. From integrating the cyclic voltammetry curve, specific capacitances of 420 F•g^－1 and 160 F•g^－1 are obtained for polyaniline and activated carbon, respectively. The cycling behavior of the hybrid electrochemical capacitor is examined in a two-electrode cell by means of cyclic voltammetry. From constant current charging and discharging test, the values for the specific energy and real specific power are 15.5 W•h•kg^－1 and 2.4 W•g^－1, respectively, in the cell voltage range between 0 and 1.4 V. The maximum specific power reach a value of 20.4 W•g^－1. The self-discharge rate of this hybrid supercapacitor is much lower than the double layer capacitor composed of activated carbon electrodes.