This paper presents polyamide (PA) nanocomposite membrane containing alumina nanoparticles synthesized via in situ interfacial polymerization. Polymerization reaction occurred from the aqueous phase of m-phenylenediamine and the organic phase of trimesoyl chloride in which alumina nanoparticles were homogeneously dispersed. In the first part of the work, aluminum oxide (Al2O3) nanoparticles with average size of 14 nm, were synthesized by an aqueous sol-gel method using precursors of aluminum nitrate and citric acid mixed solution. The as-synthesized Al2O3 nanoparticles were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDX) and Fourier transform infrared spectrometer (FTIR). In the second part, the Al2O3 were used to prepare nanoparticles entrapped PA membrane via interfacial polymerization. SEM analyis demonstrated that nanoparticles were dispersed in the membrane and embedded in polyamide chains. Elemental analysis by EDX demonstrated the presence of nanoparticles on the membrane surface. The FTIR data confirm the formation of polyamide layer with Al2O3. The performance of the nanocomposite membrane, which was cured at 80 degrees C for 5 min, was observed to be better than pristine membrane. The existence of nanoparticles in the membrane improves the permeate flux and maintains the salt rejection. It also resulted in enhanced hydrophilicity of the membranes proved by decreased water contact angle. (c) 2012 Elsevier B.V. All rights reserved.