The interaction of CO2 with a polycrystalline molybdenum-foil (Mo-foil) was previously studied at 77 K through mass-resolved Rash thermal desorption spectroscopy (FTDS). From the results, a statistical model was developed with two kinds of sites (bridge and hollow type), CO2 can adsorb on both but dissociates only on hollow ones. The proposed model reproduces the evolution of desorption peak areas as a function of CO2 exposure without using any fitting parameter. Because of the sample polycrystallinity, all desorption peaks were fitted assuming a Gaussian distribution of desorption energies with a pre-exponential factor of 10(13). Values of similar to 60.6, similar to 126.9 and similar to 158.7 kJ/mol were obtained for the desorption energies of CO2 from alpha (1), beta (1) and gamma (1) states, respectively, while 73.1 and 110.6 kJ/mol correspond to the CO alpha (2) and beta (2) desorption peaks.