In order to improve the efficiency of ruthenium dioxide, RuO2, as an electrochemical capacitor electrode, a RuO2 thin film is deposited on carbon paper and its structure and properties are evaluated. This new composite material is prepared via solution dip-coating of a Ru-ethoxide precursor and heat conversion. The coating thickness is easily controlled by varying the number of repetitions of the preparation process. The resulting structure consists of a by homogeneously coated RuO2 film on carbon paper which has a porous graphite matrix. Extensive electrochemical studies have been performed in 1 M H2SO4 electrolyte in order to evaluate the properties of the composite as an electrode in an electrochemical capacitor. The composite material shows not only high specific capacitance (620 F g(-1)) but also good power characteristics. (C) 2002 Elsevier Science B.V. All rights reserved.