Current on-site generators separate oxygen from the air using adsorption. These generators provide insufficient oxygen purity for most applications, in particular when producing high flow rates. Our technology uses a ceramic membrane that allows for fast generation of high quality oxygen at practically 100% concentration under any desired flow rate. This invention can be applied to several industries and applications such as: medicine, chemical manufacture, coal gasification, oxyfuel combustion, fish farms, aircraft, gear for trauma medicine, scuba or other breathing apparatuses.