The behavior of the nickel-based alloy Haynes 214 and the iron-based 310 stainless steel has been investigated under carburizing (ac<1) and metal dusting (ac>1) conditions within the temperature range 800-1100°C. The study involved cyclic exposure of the above alloys to commercial grade methane/hydrogen mixtures at elevated temperatures. The results indicate that no metal dusting occurs during exposure up to 500hrs. Kinetic results show higher weight gain for the alloy Haynes 214 than the 310 stainless steel during exposures at 800 and 900°C while the behavior is reversed during exposures at 1000 and 1100°C. Microstructural evaluation indicates that under carburizing conditions, Fe carbide, Cr carbide, (Fe, Cr) mixed carbide and (Cr, Mn) mixed oxide are the primary constituents of the external scale formed on 310 stainless steel exposed at 800°C, while Cr-carbides and Al2O3 constitute the primary reaction products on the surface of the alloy Haynes 214. The reason for the increase in weight gain for the alloy 214 at 800 and 900°C has been explained in terms of the formation of internal Al2O3 particles below the alloy surface. However exposure at higher temperatures promotes the formation of an external continuous protective Al2O3 layer on the alloy surface, whereas no such protective layer forms on the surface of the 310 stainless steel. The formation of this layer is apparently responsible for the immunity of the alloy 214 to severe carburization.