Abstract-GMAW is a complicated process with many interrelated parameters affecting the quality of the welded joint. The process variables with the maximum influence are the welding current, welding voltage, travel speed and arc efficiency. Response surface methodology was used to predict the weld penetration of gas metal arc welded mild steel. The experiments were conducted based on three factors, three-level, and central composite face centered design with full replications technique, and mathematical model was developed. The results obtained through response surface methodology were verified through a confirmation experiment.The welding parameters such as speed, welding current and voltage have been optimized for material AISI 1020 using GMAW process. To fortify the robustness of experimental design, a confirmation test was performed at selected optimal process parameter setting. Observations from this method may be useful for automotive sub-assemblies, shipbuilding and vessel fabricators and operators to obtain optimal welding conditions. Keywords-Gas metal arc welding, penetration, response surface methodology,central composite design.