Abstract: A process for low-temperature separation of air, wherein liquefied nitrogen and liquefied air enriched with oxygen obtained from preliminary rectification are subjected to secondary rectification to produce gaseous nitrogen containing less than 0.3 vol.% of oxygen and argon impurities, gaseous oxygen-argon mixture and liquefied oxygen-argon mixture containing up to 4.5 vol.% of argon. Subsequently, the gaseous oxygen-argon mixture is subjected to further rectification to produce argon-oxygen mixture containing argon with impurities of 3-0.1 vol.% of oxygen and less than 0.1 vol.% of nitrogen, as well as oxygen with a concentration of from 99.7 to 99.99 vol.%.