The HeI photoelectron spectra of the complexes n⁴-l- vinylnaphthalene-Fe(CO)3 and n⁴-2-vinyl-naphthalene-Fe(CO) ₃ and the free organic ligands 1-vinylnaphthalene and 2-vinylnaphthalene are measured. The spectra are interpreted on the basis of quantum-chemical calculations by the density functional method in the SVWN/6-31G(d) local density approximation and with the B3LYP/6-31G(d) hybrid exchange-correlation functional. The Kohn-Sham orbital energies with calibration corrections are shown to reproduce well the vertical ionization potentials of both the irontricarbonyl π complexes under study and their ligands. The relative ionization cross sections σ_i of the valence orbitals of the complexes are calculated in terms of the Gelius model. These quantities prove to agree perfectly with the relative ionization cross sections σ_i^exp determined experimentally from direct estimation of the band areas of the photoelectron spectra.