The electronic structure of oxygen-adsorbed Ni(1 1 0) surfaces has been studied by metastable-induced electron spectroscopy (MIES). Helium metastable atoms are de-excited both at clean and at oxygen-adsorbed Ni(1 10) surfaces through the process of resonance ionization followed by Auger neutralization (AN). The intensity of electron emission due to AN was increased by lower exposures of oxygen (similar to0.51), which is attributed to an enhanced contribution of sp-state electrons at the Ni surface to the AN process. At moderate exposures of oxygen (1-31) where the low-energy electron diffraction (LEED) pattern showed (2 x 1) reconstruction, the MIES spectra exhibited an O2p-induced peak, caused by inter-atomic Auger transition between O2p and Ni 3d states. With increasing exposure to 4 1, the LEED pattern changed to (3 x 1), while the O2p-induced peak position moved to lower energies. Variations in the local electronic structure of oxidized top-layers of the Ni(l 10) surface and the process of metastable-induced electron emission are discussed in connection with the oxygen-induced structural change. (C) 2003 Elsevier Science B.V. All rights reserved.