Abstract: The invention relates to a device for generating oxygen or a mixture of ozone and oxygen from high-purity water by means of an electrochemical cell in which a buffer vessel is provided for the high-purity water and the high-purity water can be supplied from the buffer vessel to the electrochemical cell through a feed line and oxygen or ozone and oxygen as well as high-purity water is guided from the anode chamber of the cell through a drain line directly into the buffer vessel and a feed line for the oxygen or mixture of ozone and oxygen comes out from the buffer vessel, possibly with the addition of high-purity water, to a consumer.