The composite cathodes with lanthanum-based iron and cobalt-containing perovskite La(0.6)Sr(0.4)Co(0.2)Fe(0.8)O(3.delta) (LSCF) and Ce(0.9)Gd(0.1)O(1.95) (GDC) are investigated for solid oxide fuel cell (SOFC) applications at relatively low operating temperatures (700-800 degrees C). LSCFs with high surface areas of 55 m(2)g(-1) are synthesized via a complex method with inorganic nano dispersants. The fuel cell performances of composite cathodes on anode supported SOFCs are characterized with GDC materials of surface areas of 5 m(2)g(-1) (ULSA-GDC), 12 m(2)g(-1) (LSA-GDC), and 23 m(2)g(-1) (HAS-GDC). The maximum power density of the SOFCs increases from 0.68 Wcm(-2) to 1.2 Wcm(-2) at 780 degrees C and 0.8 V as the GDC surface area increases from 5 m(2)g(-1) to 23 m(2)g(-1). The area specific resistance of the porous composite cathodes with a HAS-GDC are 0.467 ohmcm(2) at 780 degrees C and 1.086 ohmcm(2) at 680 degrees C, while these values with an LSA-GDC are 0.543 ohmcm(2) and 0.945 ohmcm(2), respectively. The best compositions of the porous composite cathodes result from the morphologies of the GDC materials at each temperature due to the formation of an electron-oxygen ion-gas boundary. Copyright (c) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.