|Abstract||Nickel base alloys are widely used in different sectors such as aerospace, nuclear, power plant, biomedical sectors etc., due to excellent mechanical properties like high hardness, high wear resistance, and corrosion resistance retained at elevated temperature applications. But the other characteristics like low thermal conductivity, low elastic modulus, strain hardening and presence of hard particles in the microstructure makes difficult in metal cutting industries. These properties increase cutting force, surface roughness, and tool wear etc. In this study, hot machining has been carried out for machining three Nickel base alloys such as Inconel 718, Inconel 625 and Monel 400 to enhanced machinability such as increase tool life, surface finish, material removal rate and reduce cutting force, tool wear and strain hardening behavior etc. FEM analysis is also carried out to validate the cutting forces, thrust forces, tool wear and chip morphology etc., and good correlation is observed. Response surface methodology (RSM) is used to predict the flank wear and surface roughness and compared with experimental results and good correlation between them is obtained. PCA base Taguchi method is also utilized to optimize the machining parameters in hot turning operation. Finally, machinability characteristics of three alloys also compared at heated and room temperature conditions.