This study examines a simulation of the performance of a system for producing hydrogen via electrolysis, using energy supplied by a photo-voltaic solar energy generator to satisfy the hydrogen consumption of the first two fuel cell buses that Madrid Municipality plans to have in service around the middle of 2003, within the CUTE program (Clean Urban Transport for Europe) of the European Union. Design stipulations were that the plant should be energetically independent, i.e. it should not require any other additional energy supply for the system to work, the system should be non-polluting at all stages, and all its components should be available in the market. A economical study of the system was also carried out, comparing its costs with those of other possible alternatives. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.