Gas separation membranes can be applied to a range of processing steps during natural gas treatment. This paper considers the current and future potential of polymeric membranes in acidic gas removal, heavy hydrocarbon recovery, water dehydration as well as nitrogen and helium separation. In particular, the current commercial membrane materials for CO2 removal (cellulose acetate, polyimides and perfluoropolymers) are reviewed, along with membrane process design and the conditions required to make membrane processes economically competitive with other technologies. The current application of membranes for heavy hydrocarbon recovery is also investigated. Issues affecting membrane viability are explored, such as competitive sorption, plasticization and the influence of module design on performance. In addition, for each application, comments are provided on the future progress of membranes in these areas. Membranes for dehydration, nitrogen separation and helium recovery are less developed, so the current potential for membranes in those applications are reviewed with a focus on the direction of future research to achieve commercially viable processes. (C) 2012 Elsevier Ltd. All rights reserved.