The thermal oxidation kinetics of cobalt disilicide on Si substrates have been investigated in the temperature range of 650–1100 °C in dry oxygen and wet oxygen. A surface layer of SiO2 grows parabolically with time. The growth rate is independent of the substrate orientation (〈111〉 or 〈100〉) and thickness of the CoSi2 layer. We surmize that the oxidation mechanism is dominated by the diffusion of an oxidant through the growing SiO2. Activation energies for the dry and wet oxidation are 1.49±0.05 eV and 1.05±0.05 eV, respectively. The kinetics is exactly the same as for NiSi2 oxidation which suggest that the same mechanism controls the oxidation of these two similar suicides.