In this paper, we report the synthesis of titanium dioxide nanoparticles (nTiO(2)) by the sol-gel method followed thermal treatment at 100, 300, 500 and 700 degrees C. The structural characterization by XRD and Rietveld refinement method confirmed the mixture of phases in the synthesized nanoparticles. Raman spectroscopy corroborated the presence of phase mixing, identifying polymorphs of TiO2. The nanoparticles exhibited spherical shape with dense appearance when investigated by FE-SEM. The band gap values obtained by diffuse reflectance resulted in the decrease of E-gap values with the increase of temperature. The catalytic study on the discoloration of the MB and RhB dyes showed great performance for nanoparticles obtained at 500 degrees C. We present the gradation ratio (%), apparent velocity constant (Kapp) and half-life time (t(1/2)) referring to 99.8% (AM) and 100% (RhB), 50.03 x 10(-3)min(-1) (AM) and 101.1 x 10(-3)min(-1) (RhB) and 13.85 min (AM) and 6.85 min (RhB), respectively.