This paper presents details of recent research progress on CO2 separation membranes and membrane processes using ionic liquids (ILs) over the past few years, including supported ionic liquid membranes (SILMs), poly(ionic liquid) membranes (PILMs), poly(ionic liquid)-ionic liquid (PIL-IL) composite membranes, polymer-ionic liquid composite membranes, ion-gel membranes, and membrane absorption processes based on ILs. Descriptions of different approaches to membrane preparation, use of gas transport mechanisms, and state-of-the-art separation results are discussed in the context of breakthroughs and challenges. Furthermore, comprehensive assessment of recently improved membranes and possible future R&D prospective are also discussed. (C) 2015 Elsevier B.V. All rights reserved.