For identification of the hydrated surface of a corrosion layer of ZrO2 formed on Zr alloys in the environment simulated the environment of a nuclear reactor, Fourier transform infra-red (FTIR) spectroscopy, Raman spectroscopy and water vapour sorption were used. Predicating ability of these methods has been verified on samples of gel coating layers produced by sol-gel synthesis, on a sample of the gel as a monolith and on powdery ZrO2, and applied to samples after exposition in autoclave at the temperature 633 K and the pressure similar to 19 MPa. The OH bands present in FTIR spectra of the model layers of hydrated ZrO2 of gel character have been found also in corrosion layers after the exposition in autoclave. This hydration ability of crystalline ZrO2 has been confirmed by sorption of water vapour on its deeply cleaned surface. From the interpretation of sorption isotherms, strong interaction of water molecules with the surface of the layer is evident pointing to a chemisorption reaction. (c) 2007 Published by Elsevier B.V.