A nickel base heat resisting alloy having high tensile strength and excellent oxidation resistance at high temperatures in the range of 1,000*-1,200*C and toughness at room temperature characterized by the alloy comprising 91-99.9 atomic percent of a basic constituent, up to 6 atomic percent silicon, and between 0.1-3 atomic percent of a second or additive constituent consisting of one or more elements selected from a group of elements consisting of titanium, chromium, zirconium, niobium, tantalum and tungsten. The basic constituent comprises nickel, aluminum and molybdenum in the following atomic percents of the basic constituent: nickel 62-83%, aluminum 11-26%, and molybdenum 6-12%. In one embodiment, the silicon comprises 0% and the basic constituent comprises between 97-99.9 atomic percent of the alloy. In the other embodiment, the silicon is in a range of 0.56 atomic percent and the basic constituent is in a range of 9199.4 atomic percent of the alloy. The addition of the silicon improves the oxidation resistance of the alloy when heated to an elevated temperature.