||TiO2 has been widely used in many research fields due to its low cost, high photocatalytic activity and high oxidation-reduction performance. In order to synthesize TiO2 nanoparticle, there are several methods such as sol-gel method, Chloride process and Sulfate process. In this study, we prepared TiO2 nanoparticles that were synthesized with various acids such as sulfuric acid, acetic acid and nitric acid by hydrothermal method. Titanium tetraisopropoxide(TTIP), ethanol and some kinds of acid were prepared to TiO2 precursor solution. The synthesized TiO2 nanoparticles crystallinity, photocatalytic activity and morphology were characterized by XRD, BET, SEM, UV-vis and TGA. UV photoactivity was analyzed via the degradation of a methylene blue.