Abstract: A device for the internal graphitization of the surface of the neck in the cone of cathode ray tubes.A device of this type comprises a frame bearing two arms, such as, capable of rotating around an axis, such as, each bearing a collar, for example, each adapted to a given type of cone. This collar has two functions: that of providing for centering along an axis (xx) of the neck of the cone and that of defining a reference line (L.sub.r).With these arms there cooperate, firstly, a supporting table on which the cone is laid and centered in a horizontal plane and, secondly, a graphitization system such that the brush in its top position reaches a determine upper limit (Lg) and, finally, a combination of means providing for the upward translational motion of the supporting table and of the graphitization system, the regulated descent of the latter, the supporting table remaining still during this stage of descent of the brush.