A ruthenium oxide coated activated carbon (RuO2/C) was synthesized as a new electrode material for aqueous electrolyte super capacitor. Some laboratory scale prototype capacitors were fabricated with the RuO2/actived carbon electrode material and tested in term of capacitance and high power discharge for their electrochemical performance.These composite super capacitors exhibited a satisfactory performance,such as the rated capacitance higher than 350 F/g,compared with that of single electrode material only.