The present paper describes a diesel fuel processor designed to produce hydrogen to feed a PEM fuel cell of 5 kW. The fuel processor includes three reactors in series: (1) oxidative steam reforming reactor: (2) one-step water gas shift reactors and (3) a preferential oxidation reactor. The design of the system was accomplished by means of a one-dimensional model. A specific study of the fuel-air mixing chamber was carried out with Fluent(R) by taking into account fuel evaporation and cool flame processes. The assembly of the installation allowed the characterisation of each component and the control of each working parameter. The first experimental results obtained in the reformer system using decaline and diesel fuels demonstrate the feasibility of the design to produce hydrogen suitable to feed a PEM fuel cell. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.