Nickel-base superalloys are widely employed in combustion turbines, reciprocating engines and exhaust systems, and other energy/power generation applications due to a combination of high strength and resistance to environmental degradation at elevated temperatures. Components fabricated from thin superalloy foil are commonly used to handle combustion product gases. Oxidation of the thin metal foil cross-section is a major concern, as minor reductions in section thickness can lead to loss of integrity and subsequent gas leakage. Water vapor, typically present in an exhaust gas stream as an unavoidable by-product of combustion, has been shown to be detrimental to the elevated temperature oxidation resistance of common iron-chromium and iron-chromium-nickel stainless steels. Accelerated attack in such environments has been observed, manifested by the formation of iron-rich oxide nodules which rapidly spread to form a thick non-protective duplex oxide scale. Extensive research has been carried out to characterize the performance of several wrought nickel-base superalloys in an attempt to identify alloys for potential service in air containing water vapor at elevated temperatures. Exposure to humidified air resulted in significant changes in oxidation behavior, with factors intrinsic to both the test environment and the sample substrate appearing to play a role in the overall resistance to environmental attack.