The poly ether-block-amide (PEBAX)/Poly-ether-imide (PEI)/SiO2 nanocomposite membranes were fabricated using the solution casting method and utilized for separation of N2, O2, CH4, and CO2 gases. The effect of SiO2 nanoparticles loading on permeability and selectivity of gases using the nanocomposite membranes was tested. The data showed that the permeability of the gases increased with increasing SiO2 nanoparticle content. dBy adding SiO2 nanoparticles (10 wt%), the permeability of N2, O2, CH4, and CO2 gases elevated from 0.39, 1, 1.83 and 11.1 to 2.01, 1.95, 2.98 and 19.83 Barrer unit, respectively (at a pressure of 2 Bar). In contrast, with increasing SiO2 content the selectivity of the studied gases decreased. The morphology, crystallinity and the functional groups of the fabricated membranes were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier- transform infrared spectroscopy (FTIR) techniques. The data presented confirm the influence of the nanoparticles on the membrane structure and thus on the permeability and selectivity of the membranes.