A comparative study is carried out on the effect of nano-sized and micron-sized Y2O3/ZrO2 (YSZ) powders on the fabrication and performance of anode-supported solid oxide fuel cells. It is found that pellets made of nano-sized YSZ powder can achieve a relative density of 96% at a sintering temperature of 1400 degreesC and 92% at sintering temperature as low as 1200 degreesC. For pellets made of micron-sized YSZ powder, densification only occurred at a sintering temperature of 1400 degreesC. On co-sintering the nano-sized YSZ electrolyte film with the anode support/substrate, the electrolyte is unable to sinter fully at 1400 degreesC, but forms a porous structure which leads to a reduced open-circuit potential and poor cell performance. This is most likely due to the nano-sized YSZ electrolyte thin film having a very low green density and there being a significant difference in the sintering behaviour of the YSZ thin layer and the Ni/YSZ cermet substrates. The sintering behaviour and the nature of YSZ powders exert a significant effect on the fabrication and performance of Ni/YSZ anode-supported thin YSZ electrolyte cells. (C) 2003 Elsevier Science B.V. All rights reserved.