Conventionally, high purity O-2 has been separated and recovered from air by cryogenic air separation plants. Recently, PSA (pressure swing adsorption) technology has improved and a new process is proposed to produce high purity O-2 by PSA. In this technology, the removal of Ar (argon) by CMS (carbon molecular sieves) and the removal of N-2 from O-2 and NZ mixtures by zeolite is the key technology for the production of high purity O-2. Concerning this technology, several patents for the production of high purity O-2 have been issued. We have conducted a series of experiments to optimize the high purity O-2 PSA process and have found an interesting result. In this paper, various factors that affect the economics of the high purity O-2 generator are discussed.