The impact of biomass-derived contaminants on solid-oxide fuel cells (SOFCs) with Ni/gadolinia-doped ceria (GDC) anodes was investigated using electrochemical impedance analysis. Measurements were carried out with symmetric test cells under a single-gas atmosphere. The impact of H2S, HCl, and naphthalene in the gas stream on the performance of Ni/GDC anodes are presented. No significant impact has been observed up to 9 ppm H2S and HCl and 110 ppm naphthalene. (c) 2007 The Electrochemical Society.