Ionic liquids (ILs) have reached an enormous interest as CO2 solvents due to their unique properties such as negligible vapour pressure and selectivity, making them very attractive in order to obtain stable supported liquid membranes. ILs containing magnetic metals in their anion are known as Magnetic Ionic Liquids (MILs) and they may show different behaviour in the presence of an external magnetic field. This work evaluates the preparation and use of a new class of supported liquid membranes based on Magnetic Ionic Liquids: Supported Magnetic Ionic Liquid Membranes (SMILMs) for CO2 separation/concentration. Four paramagnetic ionic liquids have been studied: [P-6,P-6,P-6,P-14](2)(+)[CoCl4](2-), [P-6,P-6,P-6,P-14](+)[FeCl4](-), [P-6,P-6,P-6,P-14](2)(+)[MnCl4](2-) and [P-6,P-6,P-6,P-14](3)(+)[GdCl6](3); in combination with a hydrophobic or a hydrophilic PVDF porous support. An evaluation of the membrane stability was carried out and CO2, N-2 and air permeabilites for stable SMILMs were experimentally determined. CO2/N-2 and CO2/air selectivities were estimated and introduced in the Robeson diagram for a comparison with previous reported materials. Pure gas permeation results demonstrate that these SMILMs show much higher CO2 permeabilities when comparing with N-2 and air. This selectivity may indicate a potential application of using SMILMs for the selective removal/recovery of CO2 from a gas stream and further work will perform the evaluation of an external magnetic field in the separation behaviour. (C) 2012 Elsevier B.V. All rights reserved.