Abstract: We have determined experimentally the reaction kinetics of the electrocatalytic oxidation of the trace carbon monoxide on Pt/C catalyst in aqueous sulphuric acid.At the constant potential 0.947V vs.NHE,the overall rate equation may be expressed by i=k_aP_coC_H3O⁺exp(-E_a/RT)where y is a parameter relating to the concentration of H₃O⁺.Assuming that the rate of the electrocatalytic oxidation of carbon monoxide is controlled by the edectrochemical reaction of the adsorbed COand adsorbed OHand that t the surface of catalyst is homogeneous,we can obtain a theoretical rate equation which is formally the same as the empirical rate equation.Recently,instruments for monitoring trace toxic gases in atomosphere based on electrochemical principles have been reported The determinable gases may involve CO,SO₂H₂S,nitrogen oxides,various gaseous paraffins,and so on.This new method raises wide interests for its many cdvantages,for instance,the price is cheap: the operation is simple and it can be used directly to monitor atmospheric toxic gases in situs.So far,however,the researches in these processes axe still primary The Kinetics of the electrocatalytic oxidation or reduction relating to the trace toxic gases has not been reported yet.In this paper,we shall provide the kinetic information of the electrocatalytic oxidation of the trace carbon monoxide on Pt/Cwhich may be useful for screening and improvement of electrocatalysts and also a general method for the studies of these kinetic problems.