The design of a high current transistorized potentiostat capable of delivering currents of the order of 5 amp for anodic or cathodic polarization studies at controlled potentials is presented. The range of potentials possible is determined only by the characteristics of the test electrode/solution interface. The response of this instrument is such that switching from maximum cathodic to maximum anodic potentials and vice versa can be accomplished within 10−3sec. Analysis indicates that it is possible to effect a tenfold increase in the current‐carrying capacity of this potentiostat with only minor modifications. The combination of high speed, short rise time, and high current instantly available for either anodic or cathodic polarization is unique in this potentiostat and provides outstanding versatility.