The invention relates to an electrochemical cell comprising an anode and a cathode compartments separated by a membrane, having corresponding electrodes; said anode and cathode compartments each having an external wall, flanged areas designed like frames in the contact area of the compartments, and a gas diffusion electrode comprising a liquid-permeable carrier coated with a catalyst material; said gas diffusion electrode featuring an area not coated with catalyst at its bottom edge, said area, at the bottom end of the electrochemical cell, protruding between the flanged areas of the external wall of the cathode compartment and the flanged areas of the external wall of the anode compartment in the contact area of the compartments; a porous material arranged parallel between the gas diffusion electrode and the membrane, and devices for the supply and discharge of gas and electrolyte, with a gas space separated from an electrolyte space by appropriate means.