An a‐c square wave technique was used to study resistance and double‐ layer capacity during film formation on silver electrodes in KOH solutions. The peak in the voltage‐time curve at constant current anodization is shown to coincide with complete surface coverage by Ag2O and is not an ohmic resistance, but rather an overvoltage effect. Evidence for the existence of an unstable higher oxide than normalAgO (or additional oxygen) during oxygen evolution is presented. Microvolumetric gas measurements with large area electrodes on open‐circuit decay also support this conclusion. The duration of the upper voltage plateau of the voltage‐time curve during discharge of normalAgO electrodes is determined by contact phenomena among individual normalAgO particles, in particular by separation and passivation of the remaining normalAgO by insulating surface layers of Ag2O .

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The relation between surface coverage and electrode potential during hydrogen and oxygen evolution was studied with inert electrodes of very large surface area. Desorption of gas after interruption of current was followed with micro-volumetric techniques and overvoltage decay was measured simultaneously. The steady-state overvoltage varied linearly with the total amount of hydrogen or oxygen evolved after interruption of current. The true surface area of the electrodes was determined by the BET method, and the capacity was obtained from charging curves. Average effective charges in the double layer per desorbed reacting particle were calculated from these data.

The polarization behavior of partly wetted electrodes, on which the electrode reaction proceeds beneath thin electrolyte films in the large, nonflooded pores, is described for the two cases where either diffusion through the liquid films, or the charge transfer process at the solid‐liquid interface beneath the film, are rate limiting, and whereby consideration is given to the ohmic drop in the electrolyte films and the flooding of the small pores. The treatment is verified experimentally with waterproofed porous graphite electrodes.

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