Abstract: In order to improve a generator for generating a product gas by means of a chemical reaction between an educt gas and a liquid, comprising a closed reaction chamber with a liquid supply, a liquid discharge, an educt gas supply, a product gas discharge, a liquid bath arranged within the reaction chamber and a substrate member arranged for rotation in the reaction chamber, the axis of rotation of this substrate member being arranged such that during a rotation of the substrate member at least part of the surface of the substrate member alternatingly dips into the liquid bath and emerges from the liquid bath wetted by the liquid, such that a motor arranged outside the reaction chamber for rotating the substrate member can be dispensed with and the requirement of a pressure-tight passage for a drive shaft of the substrate member through a wall of the reaction chamber is not applicable it is suggested that the generator comprise a flow generator for generating a continuous flow of the liquid in the reaction chambe