Laboratory source X-ray scattering set-up has been used to determine the complete morphology and structure of an optically important composite thin film. Analysis of grazing incidence small angle X-ray scattering, X-ray reflectivity and powder diffraction data of Au/LiNbO3 thin film prepared by sequential deposition of gold and lithium niobate on float glass substrate suggest that the Au-nanocrystallites are dispersed in amorphous medium, which although have average separation but do not have any long range periodicity other than growth or z-direction. The morphology of the nanocomposite thin film determined through X-ray scattering measurements agrees well with the measured optical absorption. (c) 2006 Elsevier B.V. All rights reserved.