Metastable TiSixNyOz films with the cubic B1-type structure were synthesized by are deposition. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and electron microprobe analysis (EMA) methods were employed to study the composition and structure of the films as a function of the are process parameters : working gas pressure, substrate temperature and potential. It was established that silicon atoms are introduced into the B1-type structure of TiNyOz films and are located in the non-metallic sublattice. The influence of the non-metallic sublattice non-stoichiometry and oxygen impurity content on the silicon concentration in the films was discussed on the basis of the experimental data obtained and the quantum chemical calculations performed.