Electrolyzed oxidizing waters (EOWs) were generated at different water flow rates, salt concentrations and water temperatures. The EOWs were stored in closed dark-brown glass bottles at room temperature for 21 days. Another duplicated set of the EOWs were stored for 12 days with four periodical openings of the screw caps. The effects of these treatments on pH, oxidation-reduction potential (ORP), electrical conductivity, total residual chlorine, dissolved oxygen (DO), sodium ion and chloride ion concentrations of the EOWs were investigated. Results indicated that pH, ORP, conductivity and chloride ion concentration did not change much under the storage conditions. Sodium ion concentration decreased 10-13% during storage. Total residual chlorine and DO decreased 24% and 21%, respectively, in the 21-day closed storage and decreased 81% and 47%, respectively, in the 12-day semi-open storage. This indicated that exposure to the atmosphere reduced more of these compounds than prolongation of the storage time. (C) 2004 Elsevier Ltd. All rights reserved.