A photocatalytic technique using Titanium Dioxide (TiO2) activated by light, due to its high oxidation efficiency, producing total decomposition of polymers (has been considered as an economical method to solve the problem of plastic waste disposal, called "white pollution"). Polypropylene (PP F401, Rompetrol Petrochemicals) nanocomposites were prepared using a commercially available TiO2 nanopowder (Degussa, P25). To study photocatalytic degradation, PP/TiO2 nanocomposites were exposed to artificial and natural light and their thermal, mechanical and morphological properties were investigated before and after the irradiation and were compared with pure PP (DMA, DSC, TGA, FT-IR, POM analysis). PP nanocomposites with 1 to 4 wt% TiO2 nanofiller were prepared by direct mixing in the Brabender Plasti-Corder mixer chamber. The samples used for thermal, mechanical and optical characterizations – square plates 150×150×0.30mm – were prepared by compression molding in an electrically heated press at 170ºC for 5 min, with a force of 50 kN. The FTIR spectra of the pure PP and PP/TiO2 nanocomposite films after UV irradiation showed the absence of carbonyl peak in the case of PP film, while in the case of nanocomposite films the intensity raises as the TiO2 content increases. DMA evidenced the stiffening effect of TiO2 nanoparticles. The magnitude of α loss modulus peak increases proportionally with the filler ratio. α relaxation from loss modulus peak shifts to higher temperatures with increasing TiO2 nanoparticle content and number hours of exposure. POM micrographs show that both the surface of PP nanocomposite and pure PP are smooth before irradiation and after 192h some cavities are formed on the surface of PP nanocomposites showing photodegradation of PP nanocomposites films comparatively with pure PP films.