Abstract: A process for production of hydrogen and/or carbon monoxide rich gas from gaseous or liquid hydrocarbon feed-stock comprising the following steps: (a) desulphurisation of the hydrocarbon feed (1), mixing the feed (1) with steam (4) produced from waste heat in the process, feeding the mixture (6, 7) to a steam reforming section (8, 9) for conversion of the hydrocarbon feed by reaction with steam to form a process gas (12) comprising a mixture of hydrogen, carbon monoxide, carbon dioxide, residual methane and excess steam, (b) cooling the process gas (12) by steam production, (c) separating hydrogen and/or carbon monoxide (21) by conducting the process gas through a hydrogen and/or carbon monoxide purification section (20), (d) adding essentially all off-gas (22) from the purification section (20) as fuel to the reforming section (8, 9) to provide heat for the reforming reaction, (e) recovering hot flue gas (32) from the reforming section and cooling the hot flue gas at least partly by steam production, (f) rec