Nanocomposite membranes were prepared by incorporation of commercial poly(ethylene glycol) functionalized polyoctahedral oligomeric silsesquioxanes (PEG-PUSS) in two grades of poly(ether-block-amide) namely PEBAX (R) MH 1657 and PEBAX (R) 2533. Single gas permeabilities of N-2, O-2, CH4, H-2, and CO2 were measured using the time-lag method. CO2 permeability increased two fold after incorporation of 30 wt% PEG-PUSS in PEBAX (R) MH 1657, while the selectivity was not significantly affected at 30 degrees C. Simultaneous enhancement in permeability and selectivity was observed up to 30 wt% loading of PEG-POSS in PEBAX (R) 2533 at 30 degrees C. The effect of temperature upon CO2 permeability and CO2 selectivity over N-2, O-2, CH4 and H-2 was studied between 30 degrees C to 70 degrees C. Substantial influence upon the thermal transition of the polyether domain of both polymers was observed due to incorporation of PEG-POSS by differential scanning calorimetry (DSC). Atomic force microscopy was used to evaluate the impact of 30 wt% PEG-POSS loading upon the surface topography of both investigated grades of PEBAX (R). Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to study the membrane morphology and the distribution of the nanofillers (PEG-POSS) in PEBAX (R) membranes. (C) 2013 Elsevier B.V. All rights reserved.