A fuel cell device includes an elongate substrate having a cold zone adjacent a first end and a reaction zone adjacent a second end configured to be heated to an operating reaction temperature while the cold zone is configured to be shielded from the heat source to remain at a low temperature below the operating reaction temperature. Fuel and air inlets positioned in the cold zone are coupled to respective elongate fuel and oxidizer passages that extend within an interior solid ceramic support structure through the reaction zone in parallel and opposing relation to respective outlets adjacent the second end. Electrodes positioned adjacent the passages in the reaction zone are each electrically coupled from the interior structure to respective exterior contact surfaces in the cold zone. A solid electrolyte monolithic with the ceramic support structure is positioned between electrodes, and electrical connections are made to the exterior contact surfaces.