Results from the European HySociety project (2003-2005) are revealed in which political, societal and technical challenges for developing a European hydrogen economy have been addressed. The focus is placed on the assessments of hydrogen pathways and infrastructure. It will show that no chain can be selected as an obvious winner according to primary energy demand, emission and cost. In order to ensure that the pathway losses are compensated by the more efficient end-use of the H-2 fuel, calculations based on well-to-tank losses and tank-to-wheel efficiencies are used. Furthermore, in order to look into the consequences of introducing hydrogen, a top-down scenario has been worked out. The message is that certainly the hydrogen distribution part for the transport application has to be improved to avoid loosing the emission gain that is obtainable, especially via carbon capture and storage Of the CO2. In order to quantify the market development a bottom-up approach has been established in particular for the transport sector. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.