New steels are being developed to achieve high creep strength as well as high resistance to oxidation in steam, to be used for new generation steam turbine components, which are expected to operate at 600-650degreesC in order to reach higher power generation efficiency. In particular, components such as steam pipes as well as turbine rotors, casings and blades must be resistant to the growth as well as to the exfoliation of oxides. New materials with very high creep strength have been developed by lowering the Cr content, but preliminary field test has shown an unacceptable high rate of oxidation and spalling. In recent studies carried out by our group within the framework of the COST 522 action, a number of commercially available coatings were explored for steam oxidation protection. These included materials known to have good high temperature oxidation resistance and deposited by techniques that can be employed to coat large steam turbine components either at the plant or at their location of manufacture, and also taking into consideration economical aspects. Promising results were obtained both at the laboratory scale as well as at field testing. For instance slurry aluminide coatings applied on P92 (9wt% Cr) are protective for at least 25,000 h at 650degreesC (tests are still ongoing). The results presented in this paper explore the behaviour of aluminide coatings applied on different steels (P22, P23 and P92). P22 and 23 are 2 wt. % Cr steels with excellent high temperature mechanical properties and are less expensive than higher Cr materials, but nevertheless exhibit much higher steam oxidation rates. The effect of Cr as well as W on the steam oxidation rate of both coated and uncoated specimens is explored. Laboratory steam oxidation testing as well as characterization of the coatings both before and after exposure will be presented. The results have provided information regarding the mechanism of protection and degradation of these coatings as well as insight for new coating development.