This paper describes the performance of a direct carbon fuel cell. Particular attention was made to investigate the effects of the composition and temperature of the electrolyte on cell operation and parameters. Various binary and ternary molten alkali hydroxides have been used as electrolytes. The performance of the fuel cell was investigated at various temperatures for four compositions of the electrolytes. Graphite rod and biochar (apple tree chips carbonized at 873 K) were used as fuels. The experiments indicated that the composition of the electrolyte and temperature significantly affected the performance of the fuel cell. The best results were obtained for the fuel cell operated with biochar fuel and NaOH-KOH electrolyte (50-50 mol%) at 673 K. (C) 2013 Elsevier B.V. All rights reserved.