Pulsed laser deposition technique was used to fabricate successfully nanostructured optical waveguide films of TiO2 and WO3-x for gas-sensing applications. High-quality mode spectra, consisting of well-defined bright mode lines were observed in the samples with smooth surface. Films' structural, morphological and optical properties as well as the chemical composition were investigated by using x-ray diffraction, scanning electron and atomic force microscopy, UV-VIS-NIR, m-line and x-ray photoelectron spectroscopy, respectively. Gas sensitivity was investigated at room temperature using m-line spectroscopy technique on basis of reversible variations of the refractive index of the samples under gas exposure. Testing scheme recording the bright m-line shift as optical response was proposed. (C) 2009 Elsevier B.V. All rights reserved.