Zn oxide, Eu oxide and Zn-Eu oxide thin films were prepared by vacuum evaporation. Their structural and optical properties have been obtained by X-ray diffractometry (XRD), energy dispersion X-ray fluorescence (EDXRF) method and spectrophotometry. The EDXRF method was used to study the composition of the deposited Zn-Eu oxide films. The XRD patterns show that the prepared thin films of Zn oxide and Zn-Eu oxide with 55% ZnO were polycrystalline, while films of Eu oxide and Zn-Eu oxide with 28% ZnO were amorphous. Spectroscopic optical constants n(lambda) and k(lambda) as well as energy gap E. were evaluated from spectrophotometry in the interband transition energy region. It was observed that Zn-Eu oxide thin films remain transparent in shorter wavelength range than the ZnO thin films, resulting from the increase of their band-gap. The energy gap of 'mixed' oxide sample is controlled by the weight fraction of the constituent oxides. It was found that n, k and transmittance values for mixed-oxide film varies smoothly between the values of the pure constituent oxides in the fundamental energy gap region. (C) 2003 Elsevier Science B.V. All rights reserved.