This paper deals with a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel – spin coating onto TCO glass plates. Films irradiated at fluence 5×1011, 3×1012, 5×1012 and 2×1013 ions cm-2, were optically characterized for band gap determination. XRD analysis revealed polytypism as both wurtzite and zincblend phases co-evolved. Scherrer’s calculations indicated grain size in nanodimensions, while SEM analysis indicated smooth surface morphology of films. Flat band potentials and donor densities were evaluated by Mott-schottky calculations. For PEC studies, thin films of ZnO were employed as working electrode in conjunction with Platinum Counter electrode, Saturated Calomel Reference electrode, 13 pH aqueous solution of NaOH as electrolyte and 150W Xenon Arc light source for illumination. A significant gain in photoelectrochemical current was recorded on SHI irradiation. The films irradiated at fluence 3×1012 ions cm-2 yielded maximum increase in photocurrent that was nearly five times compared to unirradiated samples.