We reported an asymmetric supercapacitor technology where RuO2/TiO2 nanotube composite was used as positive electrode and the activated carbon as negative electrode in 1mol/L KOH electrolyte solution. The electrochemical capacitance performance of the asymmetric supercapacitor was tested by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests. The results show that the asymmetric supercapacitor has electrochemical capacitance performance within potential range 0-1.4 V. A power density 1207 W/kg was obtained with an energy density of 5.7 W h/kg at a charge-discharge current density of 120 mA/cm(2). The supercapacitor also exhibits a good cycling performance and keep 90% of initial capacity over 1000 cycles. (C) 2005 Elsevier Ltd. All rights reserved.