AbstractMachining of nickel based alloys is one of the challenging tasks in the recent past. Wire Electrical Discharge Machine (WEDM) is an advanced machine tool, extensively used to machine hard to cut materials like nickel, titanium and other super alloys. Selection of WEDM process parameters to yield the desired level of performance measures like Material removal Rate (MRR) and Surface Roughness (SR) is crucial from quality and economic view points. In the present work an attempt has been made to investigate the effect of WEDM process parameters such as pulse on time, pulse off time, peak current and servo voltage in machining of Nimonic-263 alloy. A central composite face centered design of Response Surface Methodology (RSM) has been used for experimental plan. The significance of process parameters are estimated by ANOVA analysis. Mathematical prediction models are developed for MRR and SR by RSM. Particle Swarm Optimization (PSO) algorithm has been used to optimize the performances of the process. Results of RSM and PSO technique are compared. It has been observed that, performance of the PSO is better than that of RSM. The machining data generated for the Nimonic-263 alloy will be useful for the industry.