This paper investigates the performance of membrane gas permeation processes for simultaneous argon recovery and hydrogen concentration adjustment. A thermal plasma synthesis and subsequent water gas shift results in a feed gas mixture predominantly containing argon, hydrogen and carbon dioxide, whereby argon and a certain amount of the hydrogen have to be recycled as the plasma gas. The separation performance of two-stage processes was determined by a flow sheeting analysis using Aspen Plus. The application of different membrane materials (polyimide, PEO based Polyactive) and the adaptation of the membrane areas in the two process stages allow an independent adjustment of the hydrogen and carbon dioxide concentrations in the product stream. The influences of temperature, membrane selectivity, and recycle flow rate are discussed. For the process evaluation, an economic analysis was performed using the various membrane process designs. For the assumed costing framework, the most economic feed pressure in the membrane system is between 5 and 8 bar with an argon recovery up to 94%. The main cost per volume argon recovered of the membrane process is just 15% of today's argon prize.