Abstract The corrosion behavior of an iron–aluminum alloy with bcc structure and a composite of an iron–aluminum and a steel was studied in H 2SO 4 solution. The corrosion resistance deteriorates with increasing aluminum content of an iron–aluminum alloy. XPS measurements showed a magnetite formation on the corroded surface and a preferential corrosion of iron. The corrosion resistance for the composite of an iron–aluminum alloy and a CrMo steel is comparable to that of a CrMo steel. This implies that a corrosion-resistant composite is achievable by controlling the aluminum content of the Fe–Al alloy without the additives.