The invention relates to a membrane-electrode unit comprising a) two electrochemically active electrodes divided by a polymer electrolytic membrane, wherein the surfaces of said polymer electrolytic membrane are in contact with the electrodes in such a way that the first electrode partially or entirely covers the front side of the polymer electrolytic membrane and the second electrode partially or entirely covers the rear side thereof, b) a sealing material is applied to the front and rear sides of the polymer electrolytic membrane, wherein the polymer electrolytic membrane is provided with one or several recesses and the sealing material applied to the front side of the polymer electrolytic membrane is in contact with the sealing material applied to the rear side thereof. A method for producing said membrane-electrode unit and fuel cells provided therewith are also disclosed.