The electrochemical performance of a supercapacitor containing 40% activated carbon was investigated in different aqueous electrolytes using the galvanostatic charge-discharge technique. Average specific capacitance values were found to be 104 F/g, 92 F/g and 71 F/g respectively with 1.0 M H2SO4, 6.0 M KOH and 0.5 M Na2SO4. The highest average capacitance value (104 F/g) were achieved with sulphuric acid probably due to its higher ionic conductivity was found on the surface of the carbon electrodes. Charge-discharge cycles is based on electrostatic charge accumulation mechanism only and supercapacitor exhibited semi-capacitive and reversible behaviour similar to an electrochemical double-layer capacitor. While specific energy density value was obtained between 4-10 W h/kg, the specific power output value was between 100-1100 W/kg. Supercapacitor shows semi-capacitive and a reversible behavior and low equivalent series resistance (ESR) values (less than 1 Omega) were obtained with graphitic carbon additive. However, a good electrochemical performance depends on low (ESR) and use of electrolytes compatible with electrode material that allowing uniform pore size distribution and high surface area.