The const. potential oxidn. of adlayers of CO on a bead type Pt(111) electrode created by the impinging jet flow technique has been studied in 0.5 and 0.05 mol dm-3 H2SO4 electrolyte. Washing procedures were developed which allowed work to be carried out for long periods of time without contamination problems. At low potentials (<680 mV vs.RHE) in 0.5 mol dm-3 H2SO4 the compact adlayers were slowly oxidized in a process which first involved a const. current plateau followed by a single sym. peak. The total oxidn. charges of the transients corresponded to that of a compact CO adlayer and the peak charges to that calcd. from data reported in the literature for a looser adlayer structure. In 0.05 mol dm-3 H2SO4 the adlayers oxidize much faster and the oxidn. process is more complex. The current-time traces for the stronger electrolyte were described well by an equation esp. derived for the oxidn. kinetics under the particular conditions used in this work. Values for a potential dependent rate const. for the oxidn. were detd. by means of curve fitting.