This study investigates the machining processes of Alloy 20 under different cooling conditions: Minimum Quantity Lubrication (MQL), Carbon Dioxide (CO 2), and the hybrid MQL + CO 2 approach. The research focuses on optimizing the cutting parameters, understanding the surface characteristics, analysing the tool wear patterns, and evaluating the chip formation. Face-centred CCD-based response surface methodology (RSM) is applied in order to identify the optimized cutting conditions. Surface roughness, tool wear, and chip morphology are examined through SEM imaging. Surface roughness characteristics reveal distinctive characteristics for each coolant condition: MQL cooling results in a relatively rough surface with tool nose degradation, CO 2 cooling shows scratches on the surface and tool chipping, and MQL + CO 2 cooling yields a smoother finish with close and continuous chip formation under the optimized conditions. This study contributes valuable insights into the complex interactions between cutting parameters and coolants, aiding in the optimization of machining processes for improved outcomes of the machining of Alloy 20. Based on the RSM outcomes, the optimal parametric settings obtained are Vc = 44 m/min, f = 0.04 mm/rev, and ap = 0.43 mm.