Aluminide diffusion coatings enhance carburization and oxidation resistance of iron and nickel based alloys by formation of iron and nickel aluminides which extends the life of furnace alloys and fixtures. As a part of a large project in the Center for Heat Treating Excellence (CHTE), an aluminized coating on RA330 was studied by a hot dip process followed by diffusion heat treatment. Samples of RA330 steel were dipped in pure liquid aluminum at 700 °C for 10 minutes. After dipping, four samples were given an additional diffusion treatment. To predict the developed phases, computational analysis was used and the results were compared with the experimental data.