Abstract: Continuously operating furnace and method for obtaining thermal diffusion coating on the outside surface of metallic articles. The furnace is configured as a tunnel through which in succession are advanced closed containers filled with the processed articles and with powder mixture, containing diffusing specie. A chain conveyor, passing through the furnace, advances the containers along a transportation path. The furnace is provided with plurality of stopper means, capable to intermittently prevent the advancement of the containers and to retain them in discrete positions, situated along the transportation path. The containers advance in parallel being always directed perpendicularly to the transportation path and their retention in the discrete positions causes their rotation about their longitudinal axes. Continuous operation is associated with improved efficiency and increased capacity.