Air‐depolarized partially submerged electrodes were studied to determine the location of the zones of reaction and the rate‐controlling steps in their operation. Reaction was found to occur primarily on that part of the surface of the electrodes covered by the electrolyte meniscus. The rate‐controlling step was the diffusion of oxygen through the liquid meniscus to the electrode surface. The mass transport of oxygen as a rate‐controlling step was eliminated in a specially constructed wiped, rotating, partially submerged copper electrode. This electrode was used to measure the oxidation rate of copper at room temperature for various partial pressures of oxygen. Oxidation rates were found to be great enough to support far larger current densities than are generally attainable in normal oxygen‐electrode operation. The oxidation of copper was found to follow the logarithmic equation where was independent of oxygen partial pressure, and was proportional to the square root of the oxygen partial pressure.