a b s t r a c tBilayer gelatin/agar films containing different concentrations of TiO 2 (0.5, 1, and 2 g/100 g) were prepared by incorporation of anatase titanium dioxide nanoparticles in the fish gelatin layer of the bilayers. Gelatin/agar bilayer film was produced from the monolayers using the casting method in two steps and their microstructural, physical, mechanical and optical characteristics were studied. Results showed that the addition of TiO 2 decreased water vapor permeability of the bilayers more than 30%, upon increasing TiO 2 content to 2 (g/100 g). However, swelling ratio and moisture content increased with the increase in the nano-TiO 2 content, probably due to the hydrophilic nature of the TiO 2 nanoparticles. The tensile strength of the bilayer films increased from 10.80 to 13.91 MPa upon increasing nano-TiO 2 content from 0 to 0.5 (g/100 g); however, tensile strength decreased with further increase of the nanoparticle concentration. In addition, the metallic nature of nano-TiO 2 considerably improved the barrier properties of the bilayer films against UV light at low concentration, while it increased their opacity. This property might help in the preservation of light-sensitive foods, but more studies on real food systems are required.