Abstract In this work we present an in situ X-ray photoelectron spectroscopy (XPS) study of the growth of NiO on highly ordered pyrolitic graphite (HOPG). The XPS spectra were measured as a function of the equivalent NiO coverage. Also, ex-situ atomic force microscopy (AFM) images were taken for some of these stages in order to follow the morphology of the NiO deposits. For low coverages the lineshapes of the Ni 2p spectra differ strongly from those of bulk NiO. This has been related to the large surface contribution. The O 1s XPS spectra also show a surface related structure which follows the same trend observed in the Ni 2p spectra.