Abstract: A pressure electrolyzer having an electrolytic cell block that contains a number of electrolytic cells combined to form a stack, each electrolytic cell having an anode and a cathode. The electrolytic cell block has a sealed housing formed by a number of stacked cell frames of the electrolytic cells, the cell frames being composed at least partially of a material that is elastic at least in a longitudinal direction of the electrolytic cell block and seals adjacent cell frames from each other. End plates are provided so as to hold the electrolytic cell block in place between the end plates under compression of the elastic material. Each of the cell frames has a rigid element that runs in a circumferential direction of the frame so as to mechanically stabilize the cell frame.