A steam generating system in an oven includes an external housing which encloses an oven chamber, a hot air channel where hot air is about to flow and a hot air inlet in the form of a series of openings in the wall of the oven chamber through which hot air is blown into the oven chamber, an exhaust outlet via which hot air is removed from the oven chamber and a door. The steam generating system includes a control unit adapted to control a baking or cooking procedure by generating control signals, and an elongated steam generating module horizontally arranged in the hot air channel, the steam generating module being rotatable along a longitudinal axis and including steam module elements. Each steam module element is elongated and includes one main surface provided with a generally flat extension, the steam generating elements are arranged in parallel above each other.