To satisfy the future needs of electrical power in passenger cars and trucks, Webasto AG develops an auxiliary power unit (APU), based on a high temperature solid oxide fuel cell (SOFC). The fuel gas for the stack is generated by catalytic partial oxidation (CPO) of diesel fuel, using a reformer without an additional water supply. This minimizes system complexity, control effort and production costs. This article focuses on experimental results of a diesel reformer and the preliminary work for the supply of a suitable unit for the generation of the fuel/air mixture. Measurements of start-up and steady state operation of the vaporizer are diagrammed, followed by a brief summary of the results obtained from laboratory scale tests. Based on these results, two different CPO reformer concepts are developed and tested under realistic conditions to evaluate their potential. Finally, the current status of system integration for a self-sustaining and stand-alone diesel APU is summarized. (c) 2006 Elsevier B.V. All rights reserved.