The kinetics of CuO growth under molecular beam epitaxial (MBE) conditions has been investigated. The evaporation of Cu and its deposition onto Si(111) substrate maintained at 823 K was carried out using an electron beam heated source. For the oxidation of Cu, sources of both molecular and atomic oxygen species were employed. The films were characterized by electron spectroscopy for chemical analysis (ESCA), X-ray diffraction (XRD), infrared (IR) transmission and scanning electron microscopy (SEM). The application of a fairly high flux of molecular oxygen (3.4 x 10(20) molecules/(m(2) s)) and O-2 to Cu flux ratio of similar to 250 during the deposition was found to be insufficient to convert a detectable amount of Cu into Cu+/Cu2+ state. On the other hand, Cu2O films could be grown with relative ease by maintaining atomic oxygen flux of 1.6 times the stoichiometric value. In contrast, the kinetics of CuO formation has been found to be quite slow. For atomic oxygen to copper flux ratio of similar to 80, only similar to 95% of the copper was found to be in fully oxidized state.