This paper presents experimental results of a diesel steam reforming fuel processor operated in conjunction with a gas cleanup module and coupled operation with a PEM fuel cell. The fuel processor was operated with two different precious-metal based reformer catalysts, using diesel surrogate with a sulfur content of less than 2 ppmw as fuel. The first reformer catalyst entails an increasing residual hydrocarbon concentration for increasing reformer fuel feed. The second reformer catalyst exhibits a significantly lower residual hydrocarbon concentration in the reformate gas. Coupled operation of the fuel processor/gas cleanup with a PEM stack shows the impact of residual hydrocarbons on fuel cell performance. Using the second reformer catalyst, the fuel processor/gas cleanup was successfully coupled to an 80-cell stack generating an electric power output of up to 1.5 kW(el). The system is foreseen to be used as a mobile auxiliary power unit (APU) for caravans and yachts or as a stationary energy supply. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.