Abstract: The present invention is directed to an apparatus for electrolyzing water. The electrolyzing apparatus includes a rectangular parallelpiped shaped casing having first and second chambers through which water flows. An inlet port at the first chamber conducts water into the first chamber from outside of the apparatus. Separate first and second outlet ports at the second chamber conduct the water to outside the apparatus from the second chamber. The first and second chambers are partioned by a wall. A communication path through the wall provides communication from the first chamber to the second chamber. Anode and cathode plates are disposed within the second chamber to generate a potential difference therebetween, so that the water which flows through the second chamber is electrolyzed. The communication path includes a fluid friction generating device, such as a plurality of circular holes having various diameters which are aligned along a line perpendicular the direction of the water flow.