Dense films of (La, Sr) (Ga, Mg) O-3 compound, known as a superior oxide ion conductor, were fabricated successfully by electrophoretic deposition of the ceramic powders on graphite substrates followed by sintering with controlled heating profile. Thickness of the electrolyte films was varied in a range of ca. 40-80 mum with the deposition time. Ion conductivities of the films thus fabricated were 1.80 x 10(-2) S/cm at 600degreesC and 5.75 x 10(-2) S/cm at 730 degreesC, and were comparable to those of bulky specimens prepared in a conventional manner. A single cell was constructed on the lanthanum gallate based film with doped lanthanum cobaltite for a cathode and Ni-yittria-doped ceria for an anode. Maximum output power densities of 0.34 W/cm(2) at 600 degreesC and 0.50 W/cm(2) at 700 degreesC were attained, respectively. (C) 2003 The Electrochemical Society.