Since recently, compressed gases can substitute for hazardous solvents in the chemical industry. To meet economic and ecological demands, the reuse of compressed gas has become very desirable. This creates the need to remove, in advance, unwanted components (e.g. unconverted H-2 from hydrogenation reactions). This study examines a gas permeation process to achieve the separation of CO2/H-2 mixture under high pressure. For hydrogen separation from the mixture, a homogeneous PA6 membrane is applied at a temperature of 35 degrees C and at a pressure range between 20 and 380 bar. Due to the competitive impact of membrane compaction and swelling on the transport properties, significant changes in permeability coefficients and selectivity with feed gas composition and pressure can be observed. As reported in this paper, a substantial increase in selectivity can be gained at elevated pressures.