Abstract: The possibility of obtaining additional information on the properties of Si–SiO ₂ structures from joint analysis of the electroluminescence and cathodoluminescence spectra in the spectral range of 250–800 nm is shown. It is found that the concentration of luminescent centers responsible for the 2.2-eV band is independent from the final thickness of the oxide layer and the centers are uniformly distributed over the SiO ₂ thickness. It is shown that the luminescent centers responsible for the 4.2-eV band are characterized by a nonuniform distribution and form mainly in the outer part of the oxide layer (~30 nm) in amount proportional to the square root of the thermal oxidation time, which makes it possible to relate their formation to diffusion of oxidant components.