The present invention concerns a method and a device for processing calcinated carbon bodies such as anodes or cathodes for use in connection with electrolytic production of aluminum. The carbon bodies are processed using a rotating processing tool that includes a mainly circular disc with cutting edges mounted at its periphery. The cutting edges may be made of polycrystalline diamond (PCD) or an equivalent material. Thus, it is possible to create slots in calcinated carbon bodies in an efficient manner with low tool wear.