The technological feasibility of applying Electrophoretic Deposition (EPD) to Solid Oxide Fuel Cells (SOFCs) has been studied. Here, EPD characteristic of SOFC composition material powders has been investigated from the viewpoint of DC and AC electrochemical experiments. An electrolyte of SOFCs required gas tight dense coating. Commercial YSZ (3-8 mol% yttria stabilized zirconias) powders, as for the electrolyte materials, and various organic solvents were used in this study. In the case of 8YSZ (Tosoh, TZ-8Y) dispersed n-propanol bath, the zeta potential of 8YSZ particle showed positive and grain size distribution showed less than 0.1 mum. 8YSZ powder can be electrophoretically deposited onto the substrate because dispersed particle has charged and the charged particle acts as a migration onto the substrate by the potential gradient, and dense uniform coating was obtained less than 100 V/cm. On the other hand, as-deposited YSZ coating acts as a function of insulated layer. Potential gradient in the EPD bath has decreased because resistance of YSZ layer becomes higher than that of EPD bath with the progress of EPD under applied constant voltage. However, EPD bath characteristic itself does not change with the progress of EPD. It is suggested that the YSZ powder well dispersed EPD bath can be found by using 8YSZ and n-propanol. (C) 2004 Kluwer Academic Publishers.