A symmetrical (p/p) supercapacitor has been fabricated by making use of activated carbon (AC)-polyethylenedioxythiophene (PEDOT)-composite electrodes for the first time. The composite electrodes have been prepared via electrochemical deposition of beta-napthalenesulphonate doped PEDOT onto AC electrodes. The characteristics of the electrodes and the fabricated supercapacitor have been investigated using cyclic voltammetry (CV) and AC impedance spectroscopy. The electrodes show a maximum specific capacitance of 158 Fg(-1) at a scan rate of 10 mV s(-1). This indicates that the in situ electro-polymerization of ethylenedioxythiophene (EDOT) onto AC could improve the performance of carbon electrodes for use in supercapacitors. (c) 2007 Wiley Periodicals, Inc.