Abstract: In a known method of electrolytically marking metallic articles a hood having its bottom closed by a stencil with perforations is partially filled with an electrolyte and contains a cathode. An article to be marked is brought into contact with the stencil and constitutes the anode. The invention consists in maintaining the space within the hood at a partial vacuum sufficient to cause bubbles of air which have passed through the perforations in the stencil to flow upward in the hood, thus preventing electrolyte from seeping downward through said perforations.