Abstract: A process for producing gaseous oxygen and gaseous nitrogen by the low-temperature rectification of air in a double rectification column having a low-pressure section and a high-pressure section, comprising warming a process stream in a cold section of a reversible heat exchange zone against entering air and thereupon engine-expanding resultant warmed process stream, the improvement wherein a portion is branched off from the warmed process stream prior to its expansion, which portion is liquefield in a condenser-evaporator of the double rectifying column, is subcooled, and is then expanded into the low-pressure section (7) of the double rectifying column (8).