A Study was carried Out on the consequences of the -OHsurf/F- exchange occurring at the surface of TiO2 P25 when suspended in HF/F- solutions, The maximum extent of fluorination was readied at pH 3.0, resulting in the Fixation on the surface of ca. 2.5 F-/nm(2). The surface features Of fluorinated samples under two selected conditions were investigated by I R spectroscopy, in comparison with pristine TiO2. The collected data suggested that bridged -OHsurf/F- likely located on regular facets, was more resistant to exchange with F-. Combined high resolution transmission electron microscopy (HRTEM), inductively Coupled plasma mass spectrometry (ICP-MS) and IR measurements indicated that the fluorination performed in the adopted condition did not induce any etching of TiO2 particles, and the -OHsurf/F- exchange appeared reversible by treatment in concentrated basic solutions. Furthermore, fluorination resulted in an increase of the Lewis acid strength of surface Ti4+ sites, which, as a consequence, retained adsorbed water molecules even after outgassing at 423 K. Such an effect involved the overwhelming majority of cations exposed oil regular facets.