The effects of sulfur content, specimen thickness, and reactive element additions on the isothermal and cyclic oxidation behavior of a variety of alumina-forming alloys have been studied. These alloys include: single crystal Ni-base superalloys, ferritic Fe-Cr-Al alloys, and NiAl. The results have shown that desulfurization by hydrogen annealing decreases the amount of interface void formation and can result in improvements in cyclic oxidation comparable to that achieved by doping with reactive elements. The results have also indicated that there is less stress generation during the cyclic oxidation of Y-doped FeCrAl compared to Ti-doped or desulfurized FeCrAl. This indicates that the growth mechanism, as well as the strength of the oxide/alloy interface is influenced by Y additions, The effects of Al depletion from thin specimens, which leads to breakaway oxidation, has also been evaluated.