Abstract: Disclosed is an apparatus for high temperature treatment of rectilinear-generatrix surfaces of nonconductive products. The apparatus comprises an anode arranged opposite to a cathode to provide an arc gap therebetween for striking an arc discharge. The apparatus is further provided with a product feeding device to move the product a desired distance from the axis of the arc. The cathode is held securely in place, while the anode is positioned, integrally with the fixed cathode, to maintain a fixed position of the arc axis within the arc gap exceeding the length of the generatrix of the surface being treated. The feeding device is designed so as to provide the movement of the products in a plane extending normally to the axis of the arc when the generatrix of the surface being treated is parallel to the axis of the arc.