In this paper, poly(amide-6-b-ethylene oxide) (PEBA1657) copolymer was used to prepare polyetherimide (PEI)/PEBA1657 composite membranes and ultra thin multilayer PEI/polydimethylsilicone (PDMS)/PEBA1657/PDMS composite membranes by dip-coating method for sour gas capturing. The gas permeation and transport characteristics of sour gases (CO2, H2S, and SO2) are investigated and analyzed. With the increase of transmembrane pressure difference, the permeation of H2S, CO2, and SO2 is enhanced due to pressure-induced plasticization effect. The temperature dependency of H2S permeance for PEI/PEBA1657 composite membranes changes from positive to negative when the transmembrane pressure difference increases from 3 to 7 atm. However, the SO2 permeance of PEBA1657 composite membranes decreases dramatically with temperature increasing due to the reduction of SO2 solubility. By analyzing the difference of transport characteristics between PEI/PEBA1657 and PEI/PDMS/PEBA1657/PDMS composite membranes, PEI/PEBA1657 composite membranes with high SO2/N-2 selectivity are preferred for SO2/N-2 separation; while the multilayer PEI/PDMS/PEBA1657/PDMS composite membranes, displaying high permeances for CO2 and H2S, are suitable for CO2/N-2 and H2S/N-2 separation. (C) 2012 Elsevier B.V. All rights reserved.