Vibration-to-vibration (VV′) exchanges of excited CO with unexcited O2 are studied within the semiclassical coupled state method. For these molecules, the van der Waals component of the multidimensional potential energy surface has been imported from an accurate surface proposed recently for N2-O2 system (isoelectronic to CO-O2), while the anisotropic electrostatic contributions have been properly formulated. The VV′ rate constants are calculated for temperatures 100–1100 K. The comparison between calculated and experimentally determined rate constants for quasi-resonant VV′ exchanges at T = 150 K shows a satisfactory agreement. The rate constants calculated at T = 300 K also agree with the experimental determinations.