Abstract: In a comminution and mixing apparatus, comprising a cylindrical container (1) for receiving the material to be treated and at least one drivable stirrer which is concentrically journalled relative to the axis (20) of the container and which extends substantially up to the inner wall region of the container, there is provided at least one tool which is eccentrically and rotatably journalled relative to the container axis (20) and is mounted on the stirrer (5) for rotation together therewith. The tool can be driven either at the same rotational speeds or at a different rotational speed from the stirrer (5) and its direction of rotation can also differ from that of the stirrer. As a result of this construction of the comminution and mixing apparatus it is possible to ensure ideal conditions for mixing and comminution in which encrustations of the material being treated and the formation of lumps are avoided.