This invention relates to a process and an apparatus for the catalytic water vapor reforming of methanol. The reforming process is carried out in two stages. The methanol is incompletely reacted in the first stage in a heat-transfer-optimized process with a high specific catalyst load. In a reaction-optimized second stage, while the specific catalyst load is lower, a further reaction is carried out which completes the methanol reaction. In addition, a tube bundle reactor is disclosed in which the first, heat-transfer-optimized stage takes place in reaction tubes which, for constructing heat transfer medium ducts, are each surrounded by a concentric outer tube, while the second, reaction-optimized stage is carried out after the return of the reform gas in the housing. The reaction tubes as well as the area between the outer tubes are filled with catalyst material.