Abstract: The present invention pertains to electrolytic diaphragm cells, particularly for the electrolysis of brine to produce chlorine and caustic. The innovation resides generally in the discovery that electrolytic cell operation can be desirably enhanced by compressing the diaphragm between anode and cathode. This compression of the diaphragm reduces the diaphragm thickness from an original thickness, e.g., from an original thickness of a diaphragm freshly deposited on a cathode. The reduced thickness of the diaphragm provides for cell operation that is less than zero gap operation. By maintaining the diaphragm under compression and in a reduced thickness, the cell operates with a narrower interelectrode gap and consequently at a desirably reduced cell voltage.