Photoelectrochemical reactions at and in several redox electrolytes have been resolved into hole transfer and photocorrosion components by hydrodynamically modulated rotating disk and ring disk electrode methods. Different specimens show a range of current‐potential behavior, although parallel chemistry, with the better examples exceeding in photopotential. Both semiconductors show the same selectivity to redox couples with optimum photoelectrochemical output in solutions. Surfaces exposed to have catalytic activity for Br− oxidation. The rotating disk methods show examples (I−, ) of efficient solution hole transfer, mixed solution oxidation‐photocorrosion ( , Br−), and photocorrosion (Ti+3, Fe+2, Ce+3) at these semiconductors. The photopotential‐current characteristics indicate specific surface interactions strongly modify redox potential ordering.