This study involves the preparation and characterization of polyurethane (PU) and polyurethane/poly(e ther-block-amide) (PU/PEBA) blend membranes for gas separation. Polyurethane was synthesized by two-step polymerization based on isophorone diisocyanate (IPDI), polytetramethylene glycol (PTMG2000), 1,4-butanediamine (BDA) and 1,4-butanediol (BDO) in mole ratios of 3:1:2. Two kinds of PEBA, MV3000 and MH1657, were chosen to prepare PU/PEBA blend membranes. The effects of the blend composition on the permeability of N-2, O-2, CO2 and CH4 were investigated. All membranes were prepared by thermal phase inversion. Physical properties of synthesized polyurethane and prepared blend membranes were investigated by FT-IR, XRD and SEM analyses. FT-IR results indicate that phase separation of hard and soft segments decreased as the amount of PEBA in blend membranes increased. XRD results demonstrate that crystallinity rose by increasing the amount of PEBA in the blends. According to the SEM micrographs of the prepared samples, PU/PEBA blend membranes are miscible systems. The results of gas permeation experiments demonstrate that by increasing the amount of PEBA in PU/PEBA blend membranes, the permeability of all gases decreased while selectivity increased. (C) 2017 Elsevier B.V. All rights reserved.