Nanocrystalline TiO2 structures are formed by irradiation of 100 MeV Au8+ ion beam on amorphous thin films of TiO2. Surface morphology of the nanocrystals is studied by Atomic Force Microscopy (AFM). Amorphous to nanocrystalline phase transformation is identified by Glancing Angle X-ray Diffraction (GAXRD) and Raman spectroscopic studies. Optical characterization is carried out by UV-VIS spectroscopy technique. Blue shift observed in absorption band edge indicates the formation of nanophase TiO2 after irradiation. The impinging swift heavy ion (100 MeV Au8+) induces nucleation of nanoparticles along the ion trajectory through inelastic collisions of the projectile with electrons of the material. It is observed that the shape and size of nanoparticles formed is dependant on the irradiation fluence. (C) 2009 Elsevier B.V. All rights reserved.