Thin film solid electrolytes of La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM), Sm0.2Ce0.8O1.9 (SDC), and Sc0.11Zr0.89O2-delta (ScSZ) were deposited by RF magnetron sputtering onto single crystal sapphire substrates as well as onto porous NiO-SDC anodes at deposition temperatures of RT <= T <= 500 degrees C. The electrical conductivities, phase analyses as deposited and after annealing and microstructures of the deposited thin film electrolytes were examined. In addition, the electrochemical performance of single cells composed of Sm0.5Sr0.5O3-delta (SSC)+SDC//SDC/ScSZ//NiO+SDC was demonstrated. Impervious and highly dense bilayer thin films of SDC and ScSZ have been successfully prepared on porous NiO-SDC anodes. Maximum power densities of 360 and 240 MW cm(-2) from single cells of Sm0.5Sr0.5O3-delta (SSC)+SDC//SDC/ScSZ//NiO+SDC were obtained at 600 and 550 degrees C, respectively, under humid 20% H-2 in Ar (3% H2O) and air. RF magnetron sputtering can be applied for depositing high performance thin film electrolytes in low temperature SOFCs. (c) 2006 Elsevier B.V. All rights reserved.