Abstract: A method for monitoring and reducing corrosion in superheater and reheater furnace tubes measures electrochemical activity associated with corrosion mechanisms while corrosion is occurring at the surface of the tubes as they are exposed to combustion products. A sensor containing two electrodes spaced apart by an insulator is used. The surface of a boiler tube is one of the electrodes. The sensor is connected to a corrosion monitor. The monitor contains a computer and software, which determines a corrosion rate from the measured electrochemical activity. That rate is compared to a standard to determine if the rate is within acceptable limits. If not, the furnace operator of the furnace or an Adaptive Process Controller (APC) adjusts one or more burners to change the combustion products that are responsible for the corrosion.