Ruthenic acid nanosheet colloids were prepared by dispersing a tetrabutylammonium-ruthenic acid intercalation compound in acetonitrile or N, N-dimethylformamide. Nanosheet electrodes were fabricated on gold, indium-tin oxide (ITO)-coated glass, and ITO-coated poly(ethylene terephthalate) (PET) electrodes by electrophoretic deposition using these colloids. Transparent or flexible electrodes could be fabricated by using ITO electrodes as the substrate. The deposited amount of material could easily be controlled by the extent of deposition, which was confirmed from the linear increase in specific capacitance as a function of deposition time. The ruthenic acid nanosheet electrodes using Au substrates exhibited gravimetric capacitance of 620 F (g -RuO2)(-1). Specific capacitance of 0.82 F cm((geometric))(-2) was achieved at a scan rate of 2 mV s(-1) with a film deposited at 5 V cm(-1) for 1 h. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.2138570] All rights reserved.