The analysis of works of predecessors during the period from oxygen liquefaction and prior to the beginning of its industrial production represents the big interest. These years bases of special branch of industry have been incorporated which now is engaged in liquefaction of low-temperature gases and separation of gas mixtures, for example, separation air for reception oxygen, nitrogen and argon. Features of the basic stages of works during which oxygen was liquated at first in laboratoryare considered, and then the first liquefaction of air and oxygen plants are created. The activity of Carl von Linde and Georges Claude which stood at sources of creation known now companies «Linde» and «Air Liquide» is reported. Due to their works was possible in 20-30 of XX century to start the wide industrial production not only oxygen but other products of air separation in gaseous or liquid conditions.