An improved type of oven is disclosed for drying or curing a photosensitive material applied by coating on a substrate or board.The oven substantially comprises a substrate or board feeding station provided with a device for centering the boards, and which leads them, one by one, into the oven. Within the oven there is provided a first operating unit adapted to subject the substrates or boards to a rising motion, all the way up to the upper end thereof, where a device is provided to transfer one substrate or board at a time to a second operating unit, substantially identical to the first one, adapted to subject the substrates or boards to a lowering motion. At the lower end of the second operating unit there is provided a device for withdrawing and unloading those substrates or boards where the material has dried up or cured.A device is also provided within the oven to heat the substrates or boards and there is further provided a cooling circuit for the outgoing substrates or boards, and eventually a safety device adapted to draw a vacuum within the oven when the inspection doors are opened while the oven is operating, in order to prevent noxiuos vapours from escaping out of the oven.