Using spin polarized metastable deexcitation spectroscopy (SPMDS) we determine spin asymmetries for remanently magnetized iron(110) and cobalt(0001) films clean and oxygen covered. For clean surfaces a dominance of minority spins is observed at the Fermi edge. At the Fermi edge oxygen exposure leads to a reversal of the dominance of the spin for iron, but not for cobalt, being in agreement with theoretical calculations. An oxygen induced structure at a kinetic energy of 5.5 eV shows a dominance of minority spins, but with different dependence on coverage for iron and cobalt.