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We report on a systematic analysis of x-ray photoelectron spectroscopy (XPS) core-and valence-level spectra of clean and well-characterized iron oxide films, ie, α− Fe 2 O 3, γ− Fe 2 O 3, Fe 3− δ O 4, and Fe 3 O 4. All iron oxide films were prepared epitaxially by NO 2-assisted molecular-beam epitaxy on single crystalline MgO (100) and α− Al 2 O 3 (0001) substrates. The phase and stoichiometry of the films were controlled precisely by adjusting the NO 2 pressure during growth. The XPS spectrum of each oxide clearly showed satellite structures. These satellite structures were simulated using a cluster-model calculation, which could well reproduce the observed structures by considering the systematic changes in both the Fe 3 d to O 2 p hybridization and the d− d electron-correlation energy. The small difference in the satellite structures between α− Fe 2 O 3 and γ− Fe 2 O 3 resulted mainly from changes in the Fe-O …