Systematic analysis is carried out for 3d core photoemission spectra of rare earth oxides R2O3 and RO2 for various rare earth elements R with the use of the impurity Anderson model. We estimate the values of the charge transfer energy, the hybridization strength, etc, and discuss the mechanism of the splitting of these photoemission spectra. We also point out the reason why the RO2 structure is stable only for R = Ce1, Pr and Tb. © 1990.