The process serves for generating a pressurized product by low-temperature air fractionation. Feed air (1) is compressed (2), purified (4), cooled (9) and fed to a distillation column system (12) for nitrogen-oxygen separation (11, 23). A liquid product stream (13) is taken off from the distillation column system (12) for nitrogen-oxygen separation, brought (14) in the liquid state to an elevated pressure (PIV) and at this elevated pressure (PIV) vaporized or pseudovaporized (9). The (pseudo)vaporized product stream (16) is fed (17) as pressurized product to a gas pressure reservoir (19) which has a variable pressure (PA). The elevated pressure (PIV) is varied. The elevated pressure (PIV) is varied as a function of the pressure (PA) of the gas pressure reservoir (19).