Optical properties of Zr and ZrO2 films in the energy range from 1.5 to 100eV were obtained by quantitative analysis of reflection electron energy loss spectroscopy (REELS) and ellipsometry. The films were prepared oil (I 1 1) silicon substrates by reactive laser ablation using a zirconium target. For the growth of ZrO2 films a pressure of 5 m Torr of oxygen in the growth chamber was used. The substrate temperature during deposition was 400 degrees C. The deposits were Studied ex situ by X-ray diffraction (XRD) and in situ by X-ray photoelectron spectroscopy (XPS) and REELS. The ZrO2 films were found to be polycrystalline With monoclinic structure. The XPS results showed that the oxygen pressure used is the optimal control to produce ZrO2 films by laser ablation. A gap of 5eV for the ZrO2 film W IS measured by REELS.