We report here a single-component reactor consisting of a mixed ionic and semi-conducting material exhibiting hydrogen-air (oxygen) fuel cell reactions. The new single-component device was compared to a conventional three-component (anode/electrolyte/cathode) fuel cell showing at least as good performance. A maximum power density of 300-600 mW cm(-2) was obtained with a LiNiZn-oxide and ceria-carbonate nanocomposite material mixture at 450-550 degrees C. Adding a redox catalyst element (Fe) resulted in an improvement reaching 700 mW cm(-2) at 550 degrees C. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.