This study was carried out to evaluate the effect of blending glassy and rubbery polymers with amines in the separation of CO2/CH4 mixtures. The membranes were synthesized by PSU (glassy), PVAc (rubbery) with three different amines using the evaporation method. The theoretical performance of CO2/CH4 separation was compared against the experimental data for PSU/PVAc (80/20) wt. membrane with DEA, MDEA and MEA at 2 to 10 bar pressure. The experimental results showed that by the incorporation of PVAc and alkanolamines into base PSU, the membranes showed more efficient CO2 separation. The selectivity (CO2/CH4) of PSU/PVAc (80/20) wt. with DEA membrane was quite high, as compared to PSU/PVAc (80/20) wt. The amine polymeric blend membrane enhanced the separation of CO2 from CH4 due to adsorption to the amine groups. However, the real selectivity for binary mixtures of CO2/CH4 was lower than the theoretical selectivity. © 2019 Asociacion de Quimicos del Instituto Quimico de Sarria. All rights reserved.