We report the significance of hydrothermal temperature of TiO2 nanoparticles on the crystallinity, band gap and the photocatalytic degradation of congo red dye. These nanoparticles are synthesized by hydrothermal method at 120 ˚C, 140 ˚C and 160 ˚C. The anatase phases of the samples are confirmed from the X-ray diffraction pattern and the surface morphology of the sample is visualized in a high-resolution scanning electron microscope. The observed optical band gap value supported that TiO2 nanoparticles can be used as a visible light photocatalytic which is also in agreement with the photoluminescence spectrum. TiO2 nanoparticles prepared at 160 ˚C degrades 98.3 % of congo red in 90 min and the kinetics of degradation is analysed using both pseudo first (Langmuir Hinshelwood model) and second order equations. It is found that the pseudo second order (Blanchard) equation fits well for the whole range of degradation with the correlation coefficient of 0.9999. Manuscript profile