The high performance anode supported single cells, comprising of BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3-delta)-BCZY (Ba0.98Ce0.6Zr0.2Y0.2O3-delta)//BCZY//NiO-BCZY have been fabricated by wet powder spraying and co-firing for depositing 10-15 mu m thin film electrolytes on pre-sintered NiO-BCZY anode discs. The open circuit voltages of single cells were around 1.12-1.13 V at 600 degrees C indicating negligible gas leakage or mixed conduction through the electrolyte. The maximum power density of 493 mW cm(-2) was obtained at 600 degrees C and 0.7 V under humid air as the oxidant gas and humid 75% H-2 in N-2 (2.76% H2O) as the fuel gas at a gas flow rate of 100 ml min(-1). The area specific resistance of an anode supported button cell of BSCF-BCZY//BCZY//NiO-BCZY in fuel cell mode was about 0.46 Omega cm(2) and in the electrolysis mode was 0.26 Omega cm(2) at 600 degrees C, indicating high efficiency, reversible SOFCs. The single cell performance was stable for over 600 h at 600 degrees C. The stability of BCZY electrolyte in water-containing atmospheres was investigated by exposing sintered BCZY pellets to humid air (2.76% H2O) at 200 degrees C for 24 h or soaking them in boiling water for 3 h. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.