Pressure swing adsorption for the separation of air and other gases is carried out using specific preferred zeolite adsorbent compositions based on the symmetry of the framework atoms and cations. Particular SiO 2 /Al 2 O 3 and cation/cation ratios for enhanced performance are specified, especially LiX (SiO 2 /Al 2 O 3 ratio 2.0, 2.8, 2.364), CaLiX (2.364), CaNaX (2.364), and LiMgX (2.364).