Composite cathodes with La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF6428) and samarium-doped ceria carbonate (SDCC) were developed and investigated for solid oxide fuel cell (SOFC) applications at low operating temperatures. The LSCF-SDCC (50 wt% LSCF:50 wt% SDCC) composite cathode powders were mixed by the ball-milling technique followed by calcination at 700, 750, 800, and 850 degrees C for 2 h. To fabricate single SOFCs using LSCF-SDCC as the cathode, SDCC as the electrolyte, and NiO-SDCC as the anode, a single-step pressing and co-firing process was employed. The electrolyte-supported button cells were tested between 475 and 550 degrees C The composite cathode exhibited well-matched TEC values with the SDCC electrolyte. Calcination at lower temperatures (700 and 750 degrees C) produced powders with surface areas of 10 m(2) g(-1)-11 m(2) g(-1). Using LSCF-SDCC powders sintered at 700 and 750 C to fabricate button cells resulted in power densities of 117.9 and 120.4 mW cm(-2), respectively, at an operation temperature of 550 C with the latter cathode yielding the lowest R-p value. (C) 2013 Elsevier B.V. All rights reserved.