The electronic structure of the GdNi5 − x Cu x (x = 0, 1, and 2) compounds is studied by resonant photoemission spectroscopy, the main regularities of the electronic strucutre transformation upon substitution of copper for nickel are established, and the energies of the d and f states that form its valence bands are measured. X-ray absorption and resonant photoemission spectra at the gadolinium M 4, 5 and N 4, 5 edges and nickel and copper L 2, 3 edges are recorded. It is shown that a core photohole and an excited electron in gadolinium decay along the elastic channel; in the final state, one hole forms in the valence band and Gd 4f photoemission is enhanced tenfold. Since the inelastic Auger-type relaxation channel dominates in the transition elements with the formation of two holes in the valence band, the resonant photoemission spectrum allows us to measure the energy of two-particle interactions. The intra-atomic repulsion energy in nickel and copper is found to be ∼7 eV.