The importance of annealing process in tuning the morphological properties of membranes is obvious. In this study, poly(vinyl)alcohol as a continuous phase in nanocomposite membranes was crosslinked by mixed silanes. Tetraethylorthosilicate (TEOS) and Aminopropyltriethoxysilane (APTEOS) as two kinds of silane coupling agents go through cohydrolization and cocondensation reactions during sol-gel process to create nanoparticles in the polymer matrix. The condensation reaction is endothermic, which leads to formation of linking bonds between silica nanoparticles and polymer chains during dehydration process. This reaction is sensitive to temperature and time of annealing. The results showed that the PAT33 nanocomposite membrane performs much better separation than other prepared membranes. In this work, effects of annealing temperature and time on physicochemical properties of the prepared nanocomposite membranes and their pervaporation performance were investigated. POLYM. ENG. SCI., 50:2392-2399, 2010. (C) 2010 Society of Plastics Engineers