Anode-supported SYSZ [i.e., (Sc2O3)(0.1)(Y2O3)(0.01)(ZrO2)(0.89)] thin-film solid oxide fuel cells were evaluated between 650 and 800 degreesC. Peak power densities and power densities at cell voltages of 0.7 V were 320 and 190 mW/cm(2), respectively, at 650 degreesC, denoted as 320/190/650. Corresponding power densities at other temperature were 1400/1100/800, 990/640/750, and 600/360/700. At 750 degreesC and lower, the power densities and ASRs (area-specific resistances) were better than those reported for an 8YSZ cell with record performance [S. de Souza, S.J. Visco, L.C. De Jonghe, in Proceeding of the Second European Solid Oxide Fuel Cell Forum, edited by B. Thorstensen, vol. 2 (1996), 677.], while showing a smaller temperature dependence. Further performance improvements of about a factor of 2 were obtained at 650 degreesC after infiltration of the LSM/YSZ cathodes with a cobalt solution. This improvement persisted up to about 750 degreesC, being more pronounced at the lower temperatures. The results indicate the potential benefit of cobalt infiltration for reduced temperature SOFCs. AC measurements revealed that the majority of effect resulted from a decrease in the non-ohmic resistance of the cathode. TEM observations found similar to25 nm Co3O4 particles in the pores of the modified LSM-composite cathodes. The AC impedance response following cobalt infiltration indicates a decrease of the effective charge transfer resistance. (C) 2004 Elsevier B.V. All rights reserved.