The topic of this special issue of the Journal of Cleaner Production is “Sustainable Hydrogen from Biomass.” It is of interest to practitioners in the energy sector, governmental policy makers, researchers, educators, as well as to the general public. The purpose of this special issue is to increase public awareness and to stimulate exchange of information among actors expected to play important roles in making hydrogen available for the sustainable energy system of the future. Hydrogen as a biofuel, that is, hydrogen produced from biomass in a sustainable way is recognised as an important component of the fuel market for the future low or non-carbon based energy systems. In this special issue, the main focus is on hydrogen produced from vegetable biomass by fermentation. The development of a two-stage bioprocess for the cost-effective and environmentally friendly production of pure hydrogen from multiple biomass feedstocks is elucidated by a collection of papers presenting preliminary results of Integrated Research Project HYVOLUTION supported by the 6th Framework Programme of the European Union. The attention is turned to: - the over-all concept and characteristics of the two-stage hydrogen fermentation process, - key technological issues of fermentative hydrogen production, - the availability of vegetable feedstocks including agricultural byproducts that suitable for fermentative processing, - prospects of societal integration and sustainability of the fermentative hydrogen production technology. Other papers included in this special issue are devoted to: - simultaneous production of hydrogen and methane by fermentation of lactose-containing feedstocks derived from byproducts of milk processing, - hydrogen gas generation from organic material by electrohydrogenesis, that is, a bioelectrochemical process performed in reactors known as a microbial electrolysis cells, - the ideas for Europe-wide effort on education of hydrogen users and training of skilled staff needed for facilitating the transition to the future hydrogen economy.