At three flue gas desulfurization (FGD) systems, localized pitting corrosion, thiosulfate pitting, and crevice corrosion has occurred on the inner surfaces of fourteen stainless steel FGD reaction tanks. An electrochemical protection (EP) system is installed on each of these fourteen FGD reaction tanks to control all the previously listed forms of corrosion. Corrosion data shows that the previous corrosion is under control. Significant cost savings are realized over conventional corrosion control techniques. Key Words: acid, chloride, fluoride, flue gas desulfurization, austenitic stainless steel, corrosion, electrochemical protection, scrubbers, remote monitoring.