The design of efficient capture processes to recover carbon dioxide from combustion processes, to restrict greenhouse gas emissions, has received considerable attention. Gas permeation processes based on dense polymeric membranes are almost routinely rejected for this application. Several engineering studies conclude that absorption processes (using packed towers or membrane contactors) are the best available technology. This paper aims to provide a critical comparison of dense polymeric membrane capture processes versus amine absorption when applied in a post-combustion (i.e. flue gas treatment) situation. Technological and scientific challenges, as well as prospects for future developments are discussed. The potential of dense polymeric membranes to solve the flue gas treatment problem may have been underestimated. (C) 2007 Elsevier B.V. All rights reserved.