This paper examines a comparative assessment in terms of CO2 emissions from a hydrogen passenger train in Ontario, Canada, particularly comparing four specific propulsion technologies: (1) conventional diesel internal combustion engine (ICE), (2) electrified train, (3) hydrogen ICE, and (4) hydrogen PEM fuel cell (PEMFC) train. For the electrified train, greenhouse gases from electricity generation by natural gas and coal-burning power plants are taken into consideration. Several hydrogen production methods are also considered in this analysis, i.e., (1) steam methane reforming (SMR), (2) thermochemical copper-chlorine (Cu-Cl) cycle supplied partly by waste heat from a nuclear plant, (3) renewable energies (solar and wind power) and (4) a combined renewable energy and copper-chlorine cycle. The results show that a PEMFC powertrain fueled by hydrogen produced from combined wind energy and a copper-chlorine plant is the most environmentally friendly method, with CO2 emissions of about 9% of a conventional diesel train or electrified train that uses a coal-burning power plant to generate electricity. Hydrogen produced with a thermochemical cycle is a promising alternative to, further reduce the greenhouse gas emissions. By replacing a conventional diesel train with hydrogen ICE or PEMFC trains fueled by Cu-Cl based-hydrogen, the annual CO2 emissions are reduced by 2260 and 3318 tonnes, respectively A comparison with different types of automobile commuting scenarios to carry an equivalent number of people as a train is also conducted. On an average basis, only an electric car using renewable energy-based electricity that carries more than three people may be competitive with hydrogen trains. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.