Abstract: The invention relates to a device for generating biogas from organic materials having a biogas reactor which has a charging chamber for being charged with the organic materials and a backflow channel for an at least partial discharge of the organic materials from the biogas reactor. According to the invention it is provided that the biogas reactor in addition has at least one intermediate chamber, the charging chambers which form at least one intermediate chamber and the backflow channel form in this sequence sections of a flow path through which flow can pass in only one direction for the organic materials, two sequentially following sections respectively forming a rising flow path in one case and a falling flow path in the other. In addition the invention relates to a process for biogas generation.