The present research investigates deeply the effect of 1-ethyl-3 methylimirlazolium tetrafluoroborate ([Emim][BF4]) ionic liquid on separation performance and transport properties of poly(ether-b-amide6) (Pebax1657) at different operating pressures from 2 to 20 bar and temperatures horn 25 to 65 degrees C.[Emimi [BE4] showed interesting separation factor for CO2/light gases as a solvent and it was expected that its addition to Pebax1657 leads to more amorphous structure, thereby increasing diffusion and permeability of gases, [Emin][BF4] was added to the polymer solution up to 100 wt% of Pebax1657 weight and permeation coefficients of CO2, H-2, CH4 and N-2 through the prepared membranes were measured. The results showed remarkable increment in permeation of all the tested gases, particularly CO2 and ideal selectivity of CO2/H-2 enhanced significantly due to high solubility selectivity of the added compound. Effect of operating conditions on solubility coefficients was also investigated; thus sorption isotherms and activation energies of permeability, solubility and diffusion were calculated. In addition, the membranes were characterized by SEM, DSC, FT-IR spectroscopy and Tensile analysis to inspect changes in their physical and thermal properties, precisely. (C) 2014 Elsevier B.V. All rights reserved.