TiO 2 nanoparticles were prepared by Sol-Gel method at different pH values (4, 3.5, 3, 2.5, and 2). All samples were heated at 500°C for 18 h. The optical, morphological, and structural properties of the samples have been investigated using XRD, SEM, and UV-vis spectrophotometer techniques. The results indicated the formation of TiO 2 nanoparticles with pure Anatase phase at pH= 4 and 3.5, while further decreasing of pH, the Rutile phase start to appear intensively compare to Anatase phase. For pH=3, the ratio Rutile phase to Anatase phase was found to be around 76%.