An a‐c square wave technique was used to study resistance and double‐ layer capacity during film formation on silver electrodes in solutions. The peak in the voltage‐time curve at constant current anodization is shown to coincide with complete surface coverage by and is not an ohmic resistance, but rather an overvoltage effect. Evidence for the existence of an unstable higher oxide than (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 electrodes is determined by contact phenomena among individual particles, in particular by separation and passivation of the remaining by insulating surface layers of .