This paper describes the electrical characteristics of a small-scale SOFC system running on internally reformed butane fuel. Various oxygen-to-butane ratios were passed over anodes based on conventional Ni/YSZ and Ni/YSZ with 5% CeO2. At a ratio of 1.7 (well below the stoichiometric ratio for complete combustion), an open circuit potential of over 1000 mV was observed, and a cell current of 400 mA was obtained (approximately 100 mA/cm(2)). The cell voltage was quite stable for extended periods of time (up to 100 h), although the longevity of the cell needs to be established. Lower oxygen-to-butane ratios caused considerable coking within the cell. The system, therefore, proved to have potential for use as a possible domestic electricity generator running off an easily obtainable fuel. (C) 2000 Elsevier Science B.V. All rights reserved.