Hydrogen as a fuel for automotive engines is generally coupled with advanced conversion systems (fuel cells) but, due to energy crises and environmental pollution, hydrogen fuelling of internal combustion engines is of great interest as well. In the near-term, the use of hydrogen as gasoline additional fuel in ICE is a very interesting and accredited approach. However the employment of hydrogen introduces problems in the fuel distribution and storage systems. These drawbacks could be overcome by using on-board hydrogen production systems. In this paper, a numerical model of a simple reforming system, based on a partial oxidation process, has been developed. The model has been tested using the experimental data of a plasma-assisted reformer. The conversions of methane, propane, heptane, toluene and gasoline to hydrogen have been investigated and a thermodynamic analysis of the reforming system has been conducted by means of the AspenPlus software. The efficiency of the reformer/engine system has been also evaluated. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.