Abstract: A method and apparatus for optimizing the operating efficiency of an electrostatic precipitator based on controlling the average input power of the precipitator electrodes in response to control signals derived by sensing changes in specific instantaneous peak voltages associated with the average electrode voltages. The method is particularly well suited for electrostatic precipitators processing high resistivity fly ash and exhibiting an inflection region in its KVmin electrode voltage characteristic. The apparatus is organized to serve as a stand alone control system, or as an adjunct to existing electrostatic precipitator control systems.