Rapid thermal-cycling tests were performed for the thick-film, electrolyte-supported solid oxide fuel cells (SOFCs). The sintered yttria-stabilized zirconia (YSZ) electrolyte film was mounted on a YSZ ring by sintering the two pieces together. With this configuration, it was possible to cycle the cells between 200 and 800 degrees C with heating and cooling rates up to 50 degrees C/min. Using La0.6Sr0.4Co0.2Fe0.8O3-delta as a cathode and Ni-GDC (Gd-doped ceria) as a composite anode, the cell with a 50 mu m thick YSZ electrolyte maintained a high performance, i.e., maximum power density of similar to 510 mW/cm(2) at 800 degrees C after thermal cycles. A planar SOFC was highly durable for rapid thermal cycles.