In the present work, we have focused on the synthesis and characterization of Polystyrene (PS) nanocomposites incorporated with anatase-TiO₂. The nano-TiO₂ particles were used in two forms including surface modified (mod TiO₂) and surface unmodified (unmod TiO₂). Accordingly, two PS/TiO₂ nanocomposites were synthesized, i.e. (PS/mod TiO₂) and (PS/unmod TiO₂), starting from styrene monomer in the presence of sodium dodecylsulfate (SDS) emulsifier. 4,4′-Methylene diphenyldiisocyanate (4,4-MDI) was used for the surface modification of the nano-TiO₂ particles via urethanation reaction with terminal OH groups. After modification, optical behavior of the samples was determined. The chemical structure of pure polystyrene (pure-PS), (mod TiO₂), (PS/mod TiO₂), and (PS/unmod TiO₂) was confirmed by FT-IR spectroscopy. X-ray diffraction (XRD) analyses obviously showed the broad peak related to the (pure-PS) centered at 2θ of 20 ° as well as the sharp characteristic peak of the TiO₂ nanoparticles appeared at about 2θ of 25 °. Moreover, diffuse reflectance UV/vis spectroscopy analyses, (mod TiO₂) and (PS/mod TiO₂) samples showed strong visible absorption at the range of 400 to 600 nm.