An autoclave for pressure and temperature treatment of objects includes a pressure container having a pressure resistant wall which encloses a pressure chamber for receiving the objects to be treated, the pressure chamber having a free inner diameter of at least 1.5 m; and a heat source for heating the objects received in the pressure chamber, the heat source including a plurality of microwave sources irradiating microwave radiation, which are arranged outside the pressure container. The microwave sources are distributed over the pressure resistant wall at an areal density of at least 4 microwave sources per square meter surface area of the pressure resistant wall; and the microwave radiation irradiated by the microwave sources is coupled through the pressure resistant wall into the pressure chamber.