Ionic liquids are still a relatively new and very promising class of substances which have received increased research attention in recent years. Due to their unique physical and chemical properties these compounds are ideal for use in industrial applications and also offer a variety of very interesting possibilities in process technology, with a high potential of increasing performance and reducing investment and operating costs [1]. Ionic liquids are remarkable for their high chemical inertness and good lubricity. Therefore, one very promising application is the lubricated compression of oxygen as an alternative to the dry compression technique that has to be used because of the extremely high reactivity of pure oxygen with organic lubricating media. A screening of the relevant parameters including thermal stability, flammability, chemical inertness to pure oxygen, corrosiveness, tribological behavior and oxygen solubility was performed. Based on the results obtained, the most suitable ionic liquid was identified and used in a screw compressor setup that achieves a final pressure of 30 bar with a delivery volume of up to 200 Nm(3)/h.