A rainbow field test sponsored by the Electric Power Research Institute (EPRI) under contract RP 2465-1 was performed to evaluate the comparative hot corrosion resistance of commercially available coatings for gas turbine blades and vanes. A 10,307-hr field test was carried out on a Solar Centaur T-4000 gas turbine operating on a lower grade liquid fuel at the Owens-Illinois, Inc. glass manufacturing facility in Valera, Venezuela. This paper reviews the results of an evaluation of the performance of a simple aluminide, a Pt, Rh-aluminide and two MCrAlY (M = Co, NiCo) overlays applied to the first stage FSX-414 vanes. As found for blade coatings, on the basis of visual and metallographic examination, and remnant coating thickness measurements, it was established that the MCrAlY coatings were generally more effective than the simple aluminide and the Pt, Rh-aluminide in providing protection to first stage vanes. A remnant coating thickness index (RCTT) was used to express coating survival and protectiveness quantitatively. The results of the study have been compared with literature.