Resistance spot welding is an important manufacturing process in the automotive industry for assembling bodies. The quality and strength of the welds and, by extension, the body is mainly defined by the quality of the weld nuggets. The most effective parameters in this process are sheet material, geometry of electrodes, electrode force, current intensity, welding time and sheet thickness. The present research examined the effect of process parameters on nugget formation. A mechanical/ electrical/ thermal coupled model was created in a finite element analysis environment. The effect of welding time and current, electrode force, contact resistivity and sheet thickness was simulated to investigate the effect of these parameters on temperature of the faying surface. The physical properties of the material were defined as nonlinear and temperature dependent. The shape and size of the weld nuggets were computed and compared with experimental results from published articles. The proposed methodology allows prediction of the quality and shape of the weld nuggets as process parameters are varied. It can assist in adjusting welding parameters that eliminates the need for costly experimentation. This process can be economically optimized to manufacture quality automotive bodies.