We have studied the oxidation behavior of a hypereutectic NiAl-Mo alloy. This alloy showed an initial rapid mass loss followed by a relatively steady state behavior. The oxide scale formed during the oxidation process was seen to have a multilayered structure comprising of NiO, NiAl2O4, NiMoO4 and Al2O3 with minor amounts of MoO2 in the sub-scale region. The oxidation behavior is influenced significantly by the formation and stability of the constituent oxides, especially NiMoO4. Hence the decomposition behavior of NiMoO4 in the 1100-1200 degrees C was studied as well. The thermal decomposition of the NiMoO4 was slow at 1100 degrees C, but accelerated at 1200 degrees C, resulting in the formation of NiO, which remained in the oxide scale, and MoO3, which volatilized away. (C) 2014 Elsevier B.V. All rights reserved.