The electronic properties of fcc Fe-Co/Cu(100) were investigated by spin-resolved photoelectron spectroscopy. At a fixed concentration a dispersion of the majority and minority bands with ∆₅-symmetry towards higher binding energy along the ∆-axis of the Brillouin zone could be followed upon increasing photon energy. Upon variation of the concentration the spectra for the alloy films reveal a gradual shift of the ∆₅ minority spin band through the Fermi level and a change of the sign of the spin polarization at the Fermi level in full agreement with the expected tendency from Co to Fe. Such a behavior agrees with both a simple mixture of the Fe and Co electronic properties in a randomly mixed alloy film, and a chemical separation (clustering) of both constituents.