Fuel cells are still a new technology, and the scientific community is in dire need for reliable data on their environmental performance. In this paper a multi-criteria life cycle assessment of a prototype molten carbonate fuel cells plant is performed; the results are subject to a systematic sensitivity analysis and compared to those for three natural gas turbine plants. Results indicate an overall good environmental performance, even when compared to modem gas turbines. Possible further improvements should focus on reducing the requirement for the employed metals (e.g. Ni, Cr), as well as increasing fuel cell life time and centralising the natural gas reforming phase. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.