The gas-surface molecular exchange of CO/Pd and CO/Rh was investigated by the isotope switch method to study the chemisorption kinetics of CO on metals. Some interesting correlations were found experimentally between the rate of exchange process and the kinetics of adsorption and desorption. A concerted exchange mechanism based on the delocalized chemisorption model was postulated for better understanding of the experimental results. Analytic expressions for the adsorption and desorption kinetics of strongly bound molecules were derived which gave a satisfactory explanation for the correlation formulas obtained from the CO molecular exchange experiment. The consistent relation of the delocalization model for strong adsorption with the usual precursor theory for chemisorption is also discussed.