Abstract: Disclosed is a novel pressure swing adsorption (PSA) pre-purification process for a feed gas prior to its introduction into a cryogenic distillation unit. The PSA process uses in a multi-bed adsorbent system the steps, performed in a cyclical manner, of feed, blowdown, purge and repressurization. Optionally, a pressure equalization step is employed in the process. The resulting process provides for continual repressurization during the cycle and a constant flow rate of purified feed gas to the distillation unit.