A pressure swing adsorption process including the step of separating a gas mixture by absorbing at least one gas component in an adsorbent mass provided within each vessel of a plurality of vessels. The separating step has a single pressure equalization cycle. The separating step is preferably performed with only four valves per vessel of the plurality of vessels. Additionally, a pressure swing adsorption system of the invention includes a plurality of vessels each containing therein an adsorbent mass configured to separate a gas mixture by absorbing at least one gas component in said adsorbent mass, where the system is configured to separate the gas mixture using a single pressure equalization cycle and includes only four valves per vessel of the plurality of vessels.