Abstract: In an apparatus for treating a layer of material, particularly in a number of successive thermal treatment phases with different treatment temperatures and durations, for carrying out at least two successive treatment phases, there is provided a roller with a roller shell, on to the outer wall of which the layer of material is applied, and which is rotatably mounted about a stationary carrier. Mounted on the carrier are a number of heat-conducting lines at least equal to the number of treatment phases to be carried out. The lines extend parallel to the roller shell and are mounted behind one another in the direction of rotation of the roller shell. They comprise elements which are connected to feed ducts for tempered media and each carry a tempered or cooled medium towards the inner wall of the roller shell.