Membranes are becoming popular for CO2 separation as an environmentally friendly, efficient technology. A comprehensive review of recent studies conducted on CO2 separation from different sources is essential for tracking the progress of membrane development. This chapter reviews the recent studies conducted concerning CO2 permeation properties, breakthroughs and challenges in developing efficient CO2 separation membranes. Three main membrane categories have been reviewed in this chapter: polymeric membranes, mixed matrix membranes (MMMs), and supported ionic liquid membranes (SILMs). Studies conducted on polymeric materials and polymer blending resulted in some efficient CO2 separation membranes such as Matrimid-, 6FDA-, and Pebax-based blend membranes. Some of the MMMs that have been widely investigated have shown promising CO2 separation efficiency. For example, the combination of poly(ionic liquid)s ionic liquids, and zeolite particles resulted in highly efficient CO2/CH4 separation. Additionally, MMMs containing Pebax and zeolites showed high CO2/N2 separation. Several SILMs were investigated using different ionic liquids. Some of these SILMs achieved high CO2 permeability; however, only a few SILMs have achieved simultaneous high permeability and selectivity, including [bmim][BF4]- Ammoeng� 100-, [emim][BF4]-, and [emim][CF3SO3]-based SILMs. The main constraint of the reported membranes is the trade-off relationship between the permeability and selectivity, and both cannot be achieved simultaneously. Scopus