Ln order to apply La(Sr)CoO3 (LSC) as a cathode for medium-temperature solid oxide fuel cells without causing unfavorable solid-state reactions between LSC and yttria-stabilized zirconia electrolyte, the use of samaria-doped ceria (SDC) interlayer was examined. A porous LSC cathode prepared on a thin and dense SDC interlayer exhibited very high performance even at 800 degreesC. The performance was enhanced further by dispersing a small amount of nm-sized Pt catalysts on the LSC surface. The current density on the Pt-LSC cathode at an overpotential of - 0.05 V was 0.6 A/cm(2) at 800 degreesC in O-2. (C) 2000 Elsevier Science B.V. All rights reserved.