The successful deployment of a hydrogen delivery (transmission and distribution) infrastructure will be critical for the widespread use of hydrogen. Estimates based on three scenarios that vary in the degree of hydrogen penetration in the European energy system indicate that between 1 and 4 million km of distribution pipelines, and up to 35000 km of high-pressure transmission and 400 000 km of medium pressure sub-transmission pipelines may be needed by 2050. A truck fleet for the supply of liquefied hydrogen may reach the size of 3000-8000 vehicles. The cumulative capital necessary to build this infrastructure by 2050 may range between 700 and 2200 thousand million euros for the most optimistic scenario and is significantly lower for the other scenarios. Most of this will be needed for the development of the distribution network. These costs however represent a relatively small fraction (7.5-22%) of the annual gross value added of the energy sector. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.