Poly(tetramethylene ether) glycol (PTMEG) is used to fabricate Pebax1657/PTMEG blended membranes for CO2 separation from H-2, N-2 and CH4. Permeation of the pure gases was measured at different operating temperatures from 25 to 55 degrees C and pressures from 4 to 16 bar. The solubility and diffusion coefficients of the tested gases were also measured at 4 bar. Permeation results showed an increment in the tested gases along with enhancement in CO2/H-2 permselectivity. However, CO2/N-2 and CO2/CH4 permselectivity did not improve. The membranes were characterized by SEM, DSC, FTIR and. tensile analysis and considerable changes in morphological, thermal and structural properties of the membranes were observed. (c) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.