Anode-supported planar solid oxide fuel cells (SOFCs) with an active area of 81 cm(2) (9 cm x 9 cm) and nano-structured La0.6Sr0.4Co0.2Fe0.8O3-delta+Y2O3 stabilized ZrO2 (LSCF + YSZ) composite cathodes are successfully fabricated by tape casting, screen printing, co-firing and solution impregnation, and tested using H-2 fuel and air oxidant at various flow rates. Maximum power densities of 437 and 473 mW cm(-2) are achieved at 750 degrees C by loading 0.6 and 1.3 mg cm(-2) of LSCF in the composite cathodes, respectively. The gas flow rates, particularly the air, have a significant effect on the cell performance. Cell performance degradation with time is also observed, which is considered to be associated with the growth and coalescence of the nanosized LSCF particles in the composite cathode. The use of the LSCF cathode in combination with YSZ electrolyte without a Gd-doped CeO2 (GDC) buffer layer is proved to be applicable in large cells, even though the thermal stability of the nanosized LSCF needs to be further improved. (C) 2010 Elsevier B.V. All rights reserved.