Abstract <p> In this study, titanium dioxide (TiO₂) nanoparticles were prepared hydrolysis and condensation process. To obtain the anatase and rutile phases, the prepared product was subjected to a calcination process at a temperature of 400 and 700°C. Nanocomposites were adjusted from polymer blend of polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP) as a matrix with specific percentages (PVA 60, PEG 10, and PVP 5 wt %), and different concentrations (0 and 25 wt %) of TiO₂ NPs in the anatase and rutile phases. Several description techniques like X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and energy dispersive spectroscopy (EDS) are utilized to investigate the impact of temperature on the crystalline size, crystalline phase, and shape of produced TiO₂ nanoparticles. XRD patterns show the presence of sharp peaks which proved that it had high degree of crystallization. The anatase phase formation occurs at 400°C, while the transition to rutile phase occurred at 700°C as a result of calcination process. The crystallite size was determined using the Scherer and Williamson‒Hall (W‒H) equations, micro-strain, degree of crystallinity, volume of the unit cell, and dislocation. An increase in calcination temperature leads to increase in both crystalline size and degree of crystallinity. FE-SEM micrographs reveal that increasing the temperature led to rise the size of TiO₂ nanoparticles. In the anatase phase, the particles exhibit a spherical shape, while in the rutile phase they often have a prismatic shape. The calcination at 700°C is considered more desirable and applicable, because of the incorporation of rutile with anatase—the heterophase—into the crystal structure. It leads to synergistic effects between the two crystal structures due to increased thermodynamic stability, which makes it effective in photodegradation of various pollutants in the environment.</p>