This paper describes a preliminary study of alloys of nickel and aluminum modified with molybdenum. The purpose of this work is to develop an alloy for use under conditions of stress at temperatures of 815 °C. (1500° F.) and over. The room temperature mechanical properties of alloys of nickel and aluminum, and the influence of molybdenum on these properties, have been investigated. Certain combinations of nickel, aluminum, and molybdenum have been shown to possess tensile strengths well over 100,000 lb. per sq. in. at room temperature, and it has been demonstrated that certain characteristic microstructures, dependent upon the ratio of nickel to aluminum, are essential for the realization of these high strengths. Creep-rupture tests at 815 °C. (1500° F.) have been carried out on typical nickel–aluminum–molybdenum alloys. The results have shown that certain of these alloys are superior in many respects to existing high temperature alloys, when tested under creep-rupture conditions at 815 °C. (1500° F.). The same characteristics of microstructure that are essential for high room temperature strengths were also found to be necessary to obtain good creep-rupture characteristics at 815 °C. (1500° F.).