A steam generator with a heating gas duct which in an approximately horizontal heating gas direction is exposed to throughflow of a heating medium is provided to ensure a reliable absorption of the mentioned loads, especially of the additional loads which are produced as a result of the design dependent internal pressure of the heating gas. The heating gas duct is enclosed by a plurality of support frames which are arranged one behind the other in the heating gas direction, wherein at least two of the support frames are interconnected via a plurality of horizontal batten plates.