Methods and systems for purifying argon from a crude argon stream are disclosed, employing pressure swing adsorption at cold temperatures from −186° C. to −20° C.; more preferably from −150° C. to −50° C.; and most preferably from −130° C. to −80° C. with oxygen-selective zeolite adsorbent. In some embodiments, the oxygen-selective zeolite adsorbent is a 4A zeolite, a chabazite, or a combination thereof.