Mixed matrix membranes offer major advantages in gas separation processes due to desirable properties found in both organic and inorganic membranes. In this study, a novel mixed matrix membrane was prepared for such application by incorporating iron benzene-1,3,5-tricarboxylate (Fe-BTC) into the poly (amide-6-b-ethylene oxide) (Pebax1657) polymer. Membranes with various loadings of 5, 10, and 20 wt% Fe-BTC in the polymer matrix were fabricated to investigate the effect of filler loading on the membrane performance. Membranes, prepared by solution-casting were characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, X-ray diffraction, and tensile test. Pure gas separation of CO2, CH4, and N-2 and ideal gas selectivity of CO2/CH4 and CO2/N-2 were performed and permeation tests were carried out under 4, 8, and 12 bar pressures. Results show that adding Fe-BTC into the Pebax1657 matrix improved both permeability and selectivity of the filled membranes. For instance, 10 wt% loading of Fe-BTC into the Pebax1657 matrix led to CO2 permeability increase of 49% as well as CO2/CH4 and CO2/N-2 selectivities enhancements of about 36% and 16%, respectively. (C) 2015 Society of Plastics Engineers