FIELD: methods of removal of oxygen from starting gaseous raw material for producing oxygen-deficient retained gas. SUBSTANCE: starting gaseous raw material is fed to oxygen non-cryogenic volumetric separation system for removal of oxygen and producing oxygen-deficient raw gas product and first escaping permeant flow; oxygen-deficient t raw gas product flow is fed to separator containing main solid electrolyte ion-permeable membrane for producing second escaping permeant flow and oxygen-deficient retained gas flow. Reactive cleaning gas is added for interaction with part of oxygen penetrating through main solid electrolyte ion-permeable membrane and cleaning permeable side of this membrane. Use may be made of recycle gas flow containing at least part of one gas flow obtained in the course of process added to at least one another gas flow. EFFECT: enhanced efficiency of separation of oxygen and nitrogen from gas-and-air mixture. 10 cl, 11 dwg
