Аннотация:An intricate structure of the X-ray photoelectron spectra of valence and core electrons of potassium ferrate (VI) (K2FeO4) containing Fe6+ ions (3d2) is studied for the first time. Binding energies of core electrons Eb(Fe 3p3/2) = 57.8 eV and Eb(Fe 2p3/2) = 712.1 eV are determined. The mechanism of the appearance of the structure in the Fe 3s spectrum is investigated. The experimental Fe 3s spectrum of Fe6+(3d2) cations in K2FeO4 consists mainly of two lines with a splitting of 2.1 eV. This value is consistent with the results of the theoretical calculation (2.6 eV) for 3d2 (Fe6+) performed by the configuration interaction method.