The sol-gel route was used for the preparation of Fe/V oxide films with a molar ratio Fe:V = 1:2. Transmission electron microscopy (TEM) measurements of films prepared at 300 degrees C showed that the films consist of a FeVO4-II phase with the grains (1 nm) embedded in an amorphous phase. TEM measurements of films heated at 400 degrees C agreed with the X-ray diffraction results, confirming Fe2V4O13 grains with dimensions up to 50 nm. Charge capacities per unit thickness (Q(ins)d(-1)/Q(ext)d(-1)) were determined in a 1 M LiClO4/propylene carbonate (PC) electrolyte using cyclic voltammetry (1.5 to -1.5 V vs. Ag/AgCl, 4.8 to 1.8 V vs. Li). The LR spectroscopic result is the assignment of the bands between 1000 and 600 cm(-1) to V-O (terminal) and V-O-V/V-O-Fe (bridging) stretching modes of VO4 tetrahedra. Ex situ IR spectra of Fe2V4O13 films (400 degrees C) charged/discharged to various extents showed that at low charging (Q(ins)d(-1) (-0.13 mC cm(-2) nm(-1)) terminal and bridging modes are affected by lithium insertion. Higher chargings (Q(ins)d(-1) (-0.33 mC cm(-2) nm(-1)) result in the amorphization of the films and in the appearance of a broad absorption below 600 nm ascribed to the Li+-O modes. The optical response of films is evaluated in terms of photopic transmittance and chromaticity coordinates. Results confirmed that films are suitable for use in electrochromic transmissive (smart) windows.