Zirconium-aluminum oxide films were deposited by the pyrosol process using metallic acetylacetonates. The effect of addition of water, in volumes from 20 to 1000 mu L per 30 mL of the starting solution on the synthesis of the films deposited is analyzed. X-ray diffraction spectra show that the films are of amorphous phase. The deposition rate decreases while the aluminum incorporated in the films increases as the water volume is augmented. These behaviors are related to the action that the water molecules have on the reactants, promoting the decomposition of the reactants even at relatively low temperatures, resulting in carbon-free and transparent films. Refractive index acquires values around 1.85. Fourier transform infrared spectra show absorption bands related with vibration of Zr-O and Al-O bonds forming a ternary oxide. The energy gap determined has values of the order of 5.85 eV, which is between the values of zirconium oxide and aluminum oxide. Current-svoltage characteristics in metal-oxide-metal structures show that the effect of water is to diminish the leakage current density, although its magnitude is large. From capacitance measurements, the dielectric constant has values of the order of 23.8, which is higher than that calculated for films prepared by the same process without the addition of water. The dielectric loss factor calculated from the capacitance-voltage characteristics has high values, in agreement with the large leakage current densities observed. (c) 2006 The Electrochemical Society.