Poly vinylidene chloride (PVDC) membranes with contents of MCM-41 particles (0, 1.2 and 3wt.%, by weight of PVDC) were prepared by a phase inversion process. MCM-41 nanoparticles with 40-90 nm particle size were prepared by in situ assembly of tetraethylorthosilicate (TEOS, Merck) as inorganic precursors and cetyltrimethylammonium bromide (CTAB. Merck) then modified by polyethylene oxide (PEO) as a hydrophilicity increaser. The structure of nanoparticles was characterized by XRD. TEM, particle size analysis and N-2 adsorption techniques. The synthesized nanocomposite membranes were then characterized using scanning electron microscopy (SEM/EDX), tensile stress tests, thermogravimetric analysis (TGA), FTIR spectra, contact angle technique, water flux and BSA rejection to investigate the influence on the final properties of the developed membrane. The experiment results confirmed that the addition of modified MCM-41 particles could effectively improve membrane hydrophilicity, hydrodynamic characteristics, mechanical property, thermal stability and especially membrane flux. (C) 2011 Elsevier B.V. All rights reserved.