A reformer tube for producing synthesis gas by steam reforming of hydrocarbon-containing feed gases, preferably natural gas, includes one or more helically coiled heat exchanger tubes which are arranged within a catalyst bed of a reforming catalyst and are helically coiled over part of their length located within the catalyst bed and are otherwise straight are present, where the straight proportion of the heat exchanger tubes and/or the helix pitch of the helically coiled part alters within the catalyst bed and matching to requirements of the pressure drop, the heat exchange properties, and the corrosion resistance.