Before fabrication of dense yttria-stabilized zirconia films, several thin anode functional layers (AFL) were fabricated onto porous NiO/yttria-stabilized zirconia anode substrates using slurry spin coating. The effect of AFL thickness on gas impermeability and performance of a cell was investigated by studying the effect of AFL thickness on the open-circuit voltage, ohmic resistance, I-V characteristics and electrode overpotential of cells. The results of investigation indicated that as the AFL thickness increased, the gas impermeability of cells was generally improved and the ohmic resistance of cells was increased. The cell with a 5-mu m-thick AFL exhibited an excellent cell performance, for example, a single cell with this AFL exhibited an output power of 2.63 W cm(-2) at 800 degrees C when hydrogen was used as fuel and an oxygen was used as oxidant. (c) 2008 Elsevier Ltd. All rights reserved.