Abstract: Y--12--06 type redox resin, a copper hydrazine complex resin developed inrecent years, is used to remove dissolved oxygen from pure water in a closedrecirculating water system to minimize corrosion. The test results show that theoxygen--removing capacity of the resin is 9--13 g O_2/1 resin. In general, whenair--saturated water has been passed through the deoxygenating resin column, the oxygen content of effluent water is found to be 5--40 ppb. Over 1.5 tons deoxy-genated pure water containing oxygen less than 0.1 ppm can be obtained by eachliter redox resin. Good results can be achieved even when flow rate through thecolumn is raised to 150--fold bed volume water per hour. When deionized water ispassed first through a redox resin, and then through the mixed--bed (H--OH resin),a high quality water having a specific resistance of from 5--18×10~6 ohms--cm canbe obtained. The pH of the effluent water is 7.