We examined the neutralization of a pyridine ion, C 5 H 5 N + , when it was scattered at 20 and 40 eV off a clean metal surface, Ni(111), an oxygen adsorbed metal surface, p(2 2)O/Ni(111), and a well characterized oxide thin film, NiO(111)/Ni(111). There was a large enhancement in the scattered ion signal upon going from the clean Ni(111) to the oxygen modified surfaces at both collision energies. At 20 eV, both modified surfaces showed a 30 enhancement of the scattered ion yields with respect to the clean surface. At 40 eV, the oxygen covered surface showed a 75 enhancement while the oxide showed a 150 enhancement. These enhancements apparently resulted from oxygen-induced changes in the surface density of states which affected the resonant charge transfer of an electron from the surface to the scattered ion. These enhancements cannot be explained solely by changes in the surface work function or the surface dielectric layer thickness. Our attempts to quantitatively fit our data to resonant charge transfer models were thwarted by a variety of experimental and fundamental issues, including the fact that the scattered ion fragments from a given parent ion and energy display different normal velocities. We also observed that scattered ion signals off clean Ni(111) increased with incident ion exposure, an effect which we attribute to the chemical modification of the surface: little change was seen for the oxygen modified surfaces.