The performance of a solid oxide fuel cell fueled with flames of combustible gases, liquids, and solids was studied. A cell structure in which cells were serially integrated within a disk was also examined. Open-circuit voltages indicated with a single cell and the integrated cell were ∼0.8 and ∼3.5 V, respectively. Maximum power density obtained with the flames of n-butane, kerosine, paraffin wax (candle), and wood were respectively 75, 65, 62, and 5 mW/cm 2 . The integrated cell gave a maximum power density of 318 mW/cm 2 with n-butane flame. Fuel to air ratio distinctly influenced the output.