Y0.25Bi0.75O1.5 (YSB) thin films of 6 mu m thick were deposited on Sm0.2Ce0.8O1.90 (SDC) electrolytes via a DC magnetron sputtering technique to form highly conductive bilayered electrolytes for low-temperature solid oxide fuel cells (SOFCs). Single cells with Ni-SDC as the anode, Ag-YSB composite as the cathode, and monolayer SDC and bilayered SDC/YSB as the electrolyte were fabricated and tested using humidified H-2 as the fuel and ambient air as the oxidant. Both open circuit voltages and power densities were improved by using the bilayered electrolytes. A peak power density of 223 mWcm(-2) was obtained at 500 degrees C. Area specific polarization resistances of the Ag-YSB electrodes were also investigated using symmetrical cells with SDC and YSB as the electrolyte. (C) 2010 Elsevier B.V. All rights reserved.