Nowadays the nanoparticles have been extensively developed in food industry, particularly food packaging systems. The incorporation of nanoparticles in the packaging material can improve the mechanical, thermal and barrier properties of the packaging material. In this study, polyethylene terephthalate (PET) /TiO2 nanocomposites were prepared by melt blending of PET and TiO2 nanoparticles. The morphology of the prepared nanocomposite films was investigated by scanning electron microscopy (SEM). UV-Visible spectroscopy was used to study the transparency of prepared films. Gravimetric method was employed for measuring water vapor permeability of films. Thermal and mechanical properties were performed using differential scanning calorimetry (DSC) and tension test, respectively. The transmittance decreased considerably in TiO2 nanocomposites compared to neat polymer in both UV and visible range. The incorporation of nanofillers especially at 3% wt. loading level increased the crystallinity of PET. The results of mechanical test showed that the ductility of nanocomposites was enhanced compared to neat polymer. The parameters elongation at break and dissipated energy are measures of polymer ductility. Incorporation of nanoparticles into packaging material matrix noticeably decreased the water vapor permeability of PET. In general, TiO2 nanoparticles improved the mechanical and thermal properties of PET packages. Gas permeability of prepared nanocomposite films decreased due to increased diffusion path. Improvement of packaging material characteristics could have an interactive role in extending the shelf life of foods.