Concurrently selected thin films, such as magnetron-sputtered TiN(x)O(y) films, are deposited on flat glass for architectural purposes to reduce daylighting and solar intake in indoor environments. The luminous and solar behaviour of fenestration in real situations can be predicted if the coating structure (number of layers and thicknesses) and the material optical parameters (refractive index and absorption coefficient) are known. Unfortunately this information is often not available. Therefore a number of measurements are necessary to work out these parameters. In this paper, spectrophotometry has been applied for the optical characterization of commercial glass sheets coated with TiN(x)O(y) films. This technique was supported by X-rav specular reflectance measurements which supplied useful information about surfaces. thicknesses and layered structure of the thin film coatings.