The cyclic oxidation behavior of aluminide coatings made by low pressure chemical vapor deposition on to a new Co base superalloy DZ40M has been investigated. It was found that these coatings bonded well to the matrix well. Coating degradation when it occurs is due primarily to a depleting Al source as the oxide scale on outer surface is heated during cyclic oxidation. This degradation will be accelerated if Ti is added to the aluminizing reagent during deposition.