MCM-41 nanoparticles were prepared by in situ assembly of inorganic precursors and CTAB. The structure of nanoparticles was characterized by XRD, TEM, particle size analysis, N(2) adsorption techniques. The surface modification of particles in order to perfect dispersion in polysulfone (PSf) matrix was performed by dimethyldichlorosilane (DMDCS) and aminopropyltrimethoxysilane (APTMS) as new modification agents. Thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and SEM analysis were applied to investigate thermal stability, glass transition temperature and quality of distribution of particle in the nanocomposite membrane, respectively. The PDMS was used to coat the possible defects of synthesized membranes. For all gases (N(2), CO(2), CH(4) and O(2)) the permeance of uncoated DMDCS modified MCM-41/PSf (20 wt.%) raised from 16 to 31.6, 0.47 to 0.99, 0.45 to 1.1 and 2.75 to 5.33 for CO(2), N(2), CH4 and 02, respectively in comparison with PSf. The corresponding values of CO(2), N(2), CH(4) and O(2) permeances through uncoated APTMS modified MCM-41/PSf (20 wt.%) enhanced to 29.12, 0.85, 0.85, 4.75, respectively, compared to neat PSf membrane. Using APTMS as modification agent resulted in higher selectivity of CO(2)/CH(4) (44.23) and O(2)/N(2) (7.77) than those of DMDCS modified. The measured actual selectivities of CO(2)/CH(4) and O(2)/N(2) and permeances of all gases tested are a few amounts lower than ideal selectivities and permeances of gases in single gas permeation tests. (C) 2011 Elsevier B.V. All rights reserved.