A gadolinium-doped ceria (GDC )/scandia-stabilized zirconia (ScSZ) bilayer electrolyte on a microtubular (La,Sr)(x)MnO3-delta (LSM) support was prepared via extrusion of a microtubular cathode support and subsequent surface coatings with electrolyte and anode slurries. The GDC/ScSZ bilayer electrolyte was obtained on the LSM support using a cosintering technique, and the LSM-supported microtubular solid oxide fuel cells (SOFCs) were evaluated using field-emission scanning electron microscopy, X-ray diffraction, and electrochemical measurements in wet hydrogen (3% H2O) atmosphere. An LSM -GDC activation layer was also introduced between the cathode tube and the electrolyte layers for improvement of cell performance. The micro-SOFC exhibited a stable open-circuit voltage above 1.03 V in the temperature range from 450 to 750 degrees C, and the cell generated a maximum power density of 15, 73, 230, and 378 mW/cm(2) at 500, 600, 700, and 750 degrees C, respectively. This result indicates that our developed cosintering fabrication technology can realize a stable and high-performance, LSM-supported micro-SOFC. (c) 2008 The Electrochemical Society.