The protection efficiency against water corrosion of fluorozirconate glass, ZBLAN, dip-coated by nanocrystalline tin oxide film containing the organic molecule Tirone (R) was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical bonding structure of the surface region and morphology were studied before and after two water exposure periods of 5 and 30 min. The results of the analysis for the as-grown sample revealed a SnO1.6 phase containing carbon and sulfur, related to Tiron (R), and traces of elements related to ZBLAN (Zr, F, Ba). This fact and the clear evidence of the presence of tin oxifluoride specie (SnOxFy) indicates a diffusion of the glass components into the porous coating. After water exposure, the increase of the oxygen concentration accompanied by a strong increase of Zr, F, Ba and Na content is interpreted as filling of the nanopores of the film by glass compounds. The formation of a compact protective layer is supported by the morphological changes observed by AFM. (c) 2005 Elsevier B.V. All rights reserved.