Abstract: An underwater painting machine is provided comprising a brush for applying paint on the surface to be treated, driven with a reciprocal translational movement and cooperating with a rotary smoothing brush with axis parallel to the translational direction, wherein said application brush is formed of a plurality of tufts of bristles each fed with paint substantially at a point situated in the center of the non active end of the bristles, the paint being distributed radially and evenly in each tuft about a central channel and being guided by capillarity along the bristles as far as their active end, without the tufts being immersed in a paint filled chamber and passing through a grid.