Overvoltage measurements were made on bright platinum in sulfuric acid solutions both for the anodic evolution and the cathodic reduction of oxygen. It has been found that the experimental data are compatible with a kinetic equation of the type which was derived from a consideration of a polyelectrode model. By using the proper boundary conditions, this equation reduces to more familiar forms in certain regions. The Tafel slopes were found to be 0.122 for anodic and 0.095 for cathodic overvoltage. The io is . At the rest potential of 1.06v, a value of 0.32 µa/cm2 was calculated for the corrosion current density, im, using the derived rate equation. This value agrees well with those estimated in the literature. It is suggested that the rate‐determining step for anodic evolution of oxygen is and for cathodic reduction The reversible oxygen potential can be observed only on a completely covered surface, and the over‐all electrochemical process is in either direction. Peroxide is formed as an intermediate in the reduction of oxygen, but at the steady state concentration of 10–5 M this does not disturb the over‐all kinetics.