The paper shows the importance of soft X-ray reflection spectroscopy as a non-destructive in-depth characterization tool of the local atomic structure of high-k dielectric planar HfO2/SiO2/Si systems. The data obtained in the region of the O-K absorption edge demonstrate that the variation of the glancing angle enables the depth profilometry of the sample. By using the Kramers-Kronig analysis the reflection spectra are transformed into absorption spectra, from which the local physico-chemical environment of oxygen atoms is deduced, allowing also the knowledge of the local atomic structure and point defects associated with a thin superficial layer. (c) 2005 Elsevier B.V. All rights reserved.