To control the technological processes it is necessary to characterize the grown films using advanced methods of samples characterizations. We report on the results of depth profile studies of the contents and chemical bonding of Dy, O and Si in DyxOy films grown on n-Si (100) substrate at different conditions. The investigations were performed by x-ray photoelectron spectroscopy and Auger scanning microscopy. The studies of the morphology of crystalline structure were done by atomic force microscopy and synchrotron radiation grazing incidence diffraction. New generation of electronic, basing on nano-structures, brings new challenges for technology. One of examples is the need for new dielectrics with high dielectric constant k. Among the high-k dielectrics being studied, DyxOy appears promising due to its relatively high dielectric constant (k=12) as compared to SiO2 (k=3.9). The dysprosium oxide is characterized as chemical and thermal stable, with high breakdown electric field, low magnitude of dielectric losses and conductivity. Studies of the electrical properties of DyxOy films in the silicon MIS structures lead to promising results and suggestion to apply it as a gate insulator. The homogeneity of the gate dielectric composition and thickness and crystalline structure control are very important for reliability of the MISFET constructed with high - k dielectric. This work was supported in part within the E.C. program G1MA-CT-2002-4017 (Centre of Excellence CEPHEUS) and by the State Committee for Scientific Research (Poland) No. 72/E-67/SPB/5.PR UE/2003-2005.