The paper shows the importance of soft X-ray reflection spectroscopy as a non-destructive in-depth characterization tool for the middle atomic ordering in TiO2 thin films. The microstructure of TiO2 films synthesized by magnetron sputtering on Si(100) wafers was characterized by X-ray reflection spectroscopy (XRS), X-ray Diffraction (XRD) method and X-ray reflectometry (XRR). Reflection spectra and calculated absorption spectra were analyzed in the vicinity of Ti L2,3 and O K absorption edges. It was established that the 70 nm TiO2 film is polycrystalline with an anatase structure and homogeneous in depth. The 10 nm TiO2 film is amorphous. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.