Process for the preparation of hydrogen and carbon monoxide rich gas by steam reforming of hydrocarbon feedstock in presence of a steam reforming catalyst supported as thin film on the wall of a reactor, comprising steps of (a) optionally passing a process gas of hydrocarbon feedstock through a first reactor with a thin film of steam reforming catalyst supported on walls of the reactor in heat conducting relationship with a hot gas stream; (b) passing effluent from the first reactor to a subsequent tubular reactor being provided with a thin film of steam reforming catalyst and/or steam reforming catalyst pellets and being heated by burning of fuel, thereby obtaining a partially steam reformed gas effluent and a hot gas stream of flue gas; (c) passing the effluent from the second reactor to an autothermal reformer; and (d) withdrawing from the autothermal reformer a hot gas stream of product gas rich in hydrogen and carbon monoxide.