Energy-storage composite electrodes were prepared by mixing activated carbons (ACs) modified with nanosize titanium oxide (TiO(2)) through ultrasonic vibration in ethanol solution for 30 min. We examined the cyclic voltammetry of the composite electrodes in an aqueous electrolyte, 1 M H(2)SO(4). It was found that the specific capacitance of the composite electrodes measured in a range of 0-0.8 V was increased from 100 to 155 F/g compared electrodes comprised of ACs only. This was attributed to a reduction of polarization of the ACs modified by nanosized TiO(2). (C) 2009 Elsevier B.V. All rights reserved.