Plasma reforming could provide advantages in hydrocarbon reforming especially in small-to-medium-scale plants and in plants with fast transients. The combination of a thermal plasma reformer operating in partial oxidation mode with a catalyst bed will be described. Reduced concentrations of CO (1-3% vol) can be achieved, with high hydrogen yields and minimal plasmatron electrical power requirements. A model for the cost of hydrogen production from natural gas has been developed. The model includes hydrogen cleanup utilizing a conventional pressure swing adsorption unit. The model uses experimentally determined conversion yields and operational parameters. The conditions that result in system optimization and cost minimization have been determined. (C) 2000 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.