An integrated system for the production of hydrogen by gasification of biomass and electrolysis of water has been designed and cost estimated. The electrolyser provides part of the hydrogen product as well as the oxygen required for the oxygen blown gasifier. The production cost was estimated to 39 SEK/kg H(2) at an annual production rate of 15 000 ton, assuming 10% interest rate and an economic lifetime of 15 years. Employing gasification only to produce the same amount of hydrogen, leads to a cost figure of 37 SEK/kg H(2), and for an electrolyser only a production cost of 41 SEK/kg H(2). The distribution of capital and operating cost is quite different for the three options and a sensitivity analyses was performed for all of these. However, the lowest cost hydrogen produced with either method is at least twice as expensive as hydrogen from natural gas steam reforming. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.