In order to inhibit corrosion of carbon steel and copper alloy materials in industrial steam water cycles, it is critical to control dissolved oxygen in boiler feedwater. This article highlights the principles of thermomechanical and chemical deaeration of steam generator feedwaters and discusses the tray type and spray type deaerators and other degasification equipment. The article presents the capacities of available oxygen scavenger/reducing agent products and describes the methods for general, localized, flow-assisted corrosion control and plant best practices and troubleshooting for operational control to prevent feedwater corrosion.