Amino modified multi-walled carbon nanotubes (MWNTs-NH2) were incorporated into poly(amide-6-b-ethylene oxide) (Pebax 1657) to prepare mixed matrix membranes (MMMs). The permeation properties of CO2, N-2, CH4 and H-2 were studied and the physical properties of Pebax/MWNTs-NH2 MMMs were characterized by X-ray diffractometer (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The incorporation of MWNTs-NH2 increased the amorphous region of Pebax phase in Pebax/MWNTs-NH2 MMMs, which was beneficial for the improvement of gas permeabilities. The apparent activation energy for permeation (E-p) for CO2 decreased with the increase of pressure, while those for N-2, CH4 and H-2 almost did not change. The E-p for CO2, N-2, CH4 and H-2 slightly decreased with the incorporation of MWNTs-NH2. Compared with pristine Pebax membrane, CO2 permeability increased almost 3 times for Pebax/MWNTs-NH2 MMMs with 33 wt% MWNTs-NH2. With the increase of MWNTs-NH2 content, the normalized permeabilities of N-2, CH4 and CO2 showed almost the same increment and the selectivities of CO2/N-2, CO2/H-2 and CO2/CH4 remained constant, which were consistent with the Maxwell model prediction. Thus, the incorporation of MWNTs-NH2 significantly improved the gas permeation properties of Pebax/MWNTs-NH2 MMMs. (C) 2014 Elsevier B.V. All rights reserved.