This paper describes the development of Rene´ 125, a nickel base superalloy designed for turbine application in advanced gas turbine engines. The derivation of its composition is described. The strength of Rene´ 125 is shown to have 60° F temperature advantage over Rene´ 80, the current General Electric production turbine blade alloy. The rupture strength and creep rate of Rene´ 125 are dependent on heat treatment. When Rene´ 125 is coated with an aluminide (CODEP) there is a beneficial interaction between alloy and coating chemistries resulting in a significant improvement in the oxidation resistance of the coating. Complex cored blades have been successfully cast from Rene´ 125 and blades are currently being evaluated in engine tests.