Surfaces of mineral cuprite prepared by fracture under UHV have been characterised by synchrotron XPS and near-edge X-ray absorption spectroscopy before and after exposure to ambient air. Before exposure of the cuprite, the Cu 2p photoelectron and Cu L 2,3 -edge absorption spectra were consistent with Cu I with very little d 9 character. Surface-enhanced O 1s spectra from the unexposed mineral revealed a surface species, with binding energy 0.95±0.05eV below the principal cuprous oxide peak, assigned to under-coordinated oxygen. A second surface species, with binding energy about 1eV higher than the principal peak, was assigned to either hydroxyl derived from chemisorbed water vapour or surface oxygen dimers produced by restructuring of the cuprite fracture surface. The width of the principal O 1s peak was 0.66±0.02eV. The observed Cu L 3 - and O K-edge absorption spectra were in good agreement with those simulated for the cuprite structure. After exposure of the fracture surface to ambient air, the low binding energy O 1s surface species was barely discernible, the original high binding energy O 1s surface species remained of comparable intensity, new intensity appeared at an even higher (∼1.9eV) binding energy, and the Cu L 2,3 -edge spectrum indicated the presence of Cu II , consistent with the formation of a thin surface layer of Cu(OH) 2 .