Abstract: An apparatus for producing high purity oxygen and nitrogen in the liquid and gaseous phases. The apparatus is a modular, mobile system employing a low design operating pressure. The system purifies ambient air through filters and a dual immobilized fixed bed molecular sieve type pressure swing adsorber prior to the cryogenic distillation of the air. Through the incorporation of the pressure swing adsorber having a high frequency regeneration cycle, the disclosed system provides a reduced system size. The configured system employs waste gas from the distillation process to purge the pressure swing adsorber. The cryogenic distillation procedure includes a heat exchanger, a turboexpander, high and low pressure distillation columns, a subcooler and a condenser.