Vanadium oxide (V 2 O 5 ) films were prepared by dip-coating from V-oxoisopropoxide sols and heating at 300ЊC for 1 h. Transmission electron microscopy combined with small area electron and X-ray diffraction revealed that the films consist of disordered V 2 O 5 grains with an orthorombic structure (P mmn ). Electromotor force (emf), cyclic voltammetric (CV), and chronocoulometric measurements, combined with in situ ultraviolet-visible (UV-vis) spectroelectrochemical measurements, revealed similar electrochromic and electrochemical properties with other sputtered and sol-gel derived V 2 O 5 films. IR absorbance and reflectionabsorption spectra, performed at near-grazing incidence angle (NGIA) conditions (80Њ, P-polarized), allowed us to compare the observed transverse optical (TO) and longitudinal optical (LO) frequencies of films with the TO and LO mode frequencies obtained from the dispersion analyses of V 2 O 5 crystalline reflection IR spectra. TO and LO spectra of charged films show that Li ϩ ...O interactions modify the terminal V-O A (vanadyl), bridging V-O B -V, and edge-sharing V-O C stretching frequencies, suggesting that these interactions take place between the oxygens bordering the cavities in which Li ϩ ions are accommodated during charging. The red-frequency shift of the V-O A stretchings [1016 cm Ϫ1 (TO), 1035 cm Ϫ1 (LO)] and the disappearance of the bridging V-O B -V stretching mode [795 cm Ϫ1 (TO), 895 cm Ϫ1 (LO)] can be used as a diagnostic tool to differentiate between films cycled in the safe and unsafe potential regions. A polaron absorption was observed above 2000 cm Ϫ1 in the ex situ TO and in situ NGIA reflectionabsorption (LO) spectra of films charged in the safe potential region.