A device for pyrolysis of a material has a horizontal receiving chamber, a horizontally moving compressing element compressing the material in the receiving chamber to form a compact body, a horizontal pyrolysis chamber communicating with the receiving chamber and subjecting the compact body to a heat treatment, a separating partition separating the chambers, and a cylinder-piston unit with a compressing plate which, with the closed partition, first compresses the material in the receiving chamber, then after vertically withdrawing the partition, moves the compressed material from the receiving chamber into pyrolysis chamber and is heated there to produce pyrolysis gas.