This paper reports about the fine structure in the O—K-spectra of the oxides BeO, MgO, CaO, SrO, BaO, Sc 2 O 5 , Y 2 O 3 , La 2 O 3 , Sm 2 O 3 , Yb 2 O 3 , NiO and ZnO. The spectra show the satellite lines α 3 , α 4 , α 5 , α 6 on the short wavelength side of the main line α 1,2 and a shoulder β′ on its long wavelength side. The wavelengths of all lines depend on the nature of the oxide. For the positions of the lines K α1.2 in the spectra no systematic relation to other data of the oxides is observed. On the other hand the distance of the a 4 -satellite from the α1,2 -line decreases with increasing electronegativity of the metal atom in the oxide. This distance can be used as a measure for the ionic character of the metal-oxygen bond in these compounds.