Abstract : The preparation and characterization of high surface area ruthenium/carbon aerogel composite electrodes for use in electrochemical capacitors is reported. These new materials have been prepared by the chemical vapor impregnation of ruthenium into carbon aerogels to produce a uniform distribution of adherent approx. 2 nm nanoparticles on the aerogel surface. The electrochemically oxidized ruthenium particles contribute a pseudocapacitance to the electrode and dramatically improve the energy storage characteristics of the aerogel. These composites have demonstrated specific capacitances in excess of 200 F/g, in comparison to 95 F/g for the untreated aerogel.