We present the results of the preparation and characterization of ITO transparent conducting layers (In2O3:Sn) on glass substrates by the sol–gel process. The chemical and physical parameters in the preparation of the solution and during the deposition of the films were changed, in order to analyze the structural, optical and electrical results having in mind the great technological applications of this material. The crystallographic properties and the average grain size were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical parameters (band gap, refraction index and absorption coefficient) were determined by spectral transmittance and using a simulation software. The electrical characterization was done by the four-point probe method to determine the sheet resistance and resistivity. The films with a sheet resistance of 167.3 Ω/□, and 92.7% transmittance, average grain size of 32.7 nm and cubic structure with a lattice parameter of 10.12 Å were obtained. With the obtained appropriate parameters, low resistivity and highly transparent films, ideal for applications as contact in optical windows in solar cells, smart windows and others can prepared.