Ruthenium oxide films were grown on metal substrates at temperatures from 100 to 300 degreesC using a ruthenium ethoxide solution as the precursor. The amorphous phase and highly porous ruthenium oxide films were formed at temperatures of 200 degreesC and lower. A specific capacitance of 593 F/g and an interfacial capacitance of 4 F/cm(2) were measured from a single-cell capacitor made with ruthenium oxide film electrodes prepared at 200 degreesC. The specific capacitance as a function of temperature and film thickness was studied. A comparison of the surface morphology and electrochemical properties for ruthenium oxide film electrodes made by the ruthenium ethoxide precursor and the ruthenium chloride precursor was also made.