AN APPARATUS FOR THE ELECTROCHEMICAL MACHINING OF FLAT METAL SURFACES WHICH UTILIZES A POOL OF VISCOUS ELECTROLYTE OF SUFFICIENT VISCOSITY TO SUPPORT A WORKPIECE AND SPACE THE WORKPIECE VERY SLIGHTLY FROM THE SURFACE PLATE, AS WELL AS TO FACILITATE MOVEMENT OF THE WORKPIECE OVER THE SURFACE PLATE. MOVEMENT OF THE WORKPIECE IN COMBINATION WITH VARIOUS VISCOSITES OF THE VISCOUS ELECTROLYTE ARE UTILIIZED TO OBTAIN THE DEGREE OF FLATNESS DESIRED.