Process for the preparation of hydrogen by reacting a feed gas comprising methane and carbon monoxide with steam in the presence of a steam reforming catalyst at a pressure of at least 15 bara in the heated zone of a steam reformer to obtain a raw hydrogen containing product stream, wherein (a) the feed gas is mixed with the steam before entering the steam reformer resulting in a reaction mixture of the feed gas and steam having a temperature below 540° C.; and (b) the reaction mixture obtained in step (a) is fed into the heated zone of the steam reformer where it is first contacted with an inert material before it is contacted with the steam reforming catalyst.