Abstract: In order to generate a highly compressed gas, a multistage high-pressure compressor is used, which has a number of 3 compressor stages (10a, 10b, 10c, 10d). A vortex tube (20a, 20b, 20c, 20d) is connected downstream from these compressor stages (10a, 10b, 10c, 10d). The pressure difference between the pressure line (4) of the high-pressure compressor and the compressed gas reservoir (7) to be filled is used for driving, together with an expansion turbine (5), a pre-compressor (2) for pre-compressing the gas before entering the first compressor stage (10a). Alternatively, a vortex tube for cooling gas can be mounted between the last compressor stage (10d) and the compressed gas reservoir (7). The inventive device permits a direct filling of a compressed gas reservoir in order to reach a limit value of the pressure in the compressed gas reservoir at a predetermined limit temperature, said limit value being stipulated according to the technical rules.