The irradiation effect of 350 MeV Au+ ions on Ti/Si multilayers has been studied using Rutherford backscattering spectroscopy, X-ray reflectivity (XRR) and grazing incidence X-ray diffraction (GIXRD). Intermixing effects have been studied as a function of fluences of 0.46 x 10(14), 1.82 x 10(14) and 4.62 x 10(14) cm(-2). Rutherford backscattering spectra (RBS) confirm mixing at the interface. X-ray reflectivity patterns show damage at the interfaces with the absence of a continuous fringe pattern at high fluence doses in comparison to the pristine interface. Mixing leads to titanium di-silicide (TiSi2) Phase formation as a shown by grazing incidence X-ray diffraction patterns. The observed intermixing is attributed to energy deposited by the incident ions in the electronic system of the target. Swift heavy ion irradiation induced inter-mixing increases with fluence. (c) 2005 Elsevier B.V. All rights reserved.