In the present study, Galvannealed High strength Interstitial Free (HIF) steel sheets and Dual Phase (DP 590) steel sheets were used for the investigations. For Galvannealed HIF steel sheets resistance spot weld joints, the variation in dynamic contact resistance (DCR) with the change in welding process parameters such as weld current, weld time and electrode force were used for establishing the range of adequate nugget formation parameters. Influence of these process parameters over the shear – tensile strength, nugget diameter and the observed failure mode was studied using one factor at a time (OFAT) approach. A critical nugget diameter distinguishing between the Interfacial Failure and Pull out Failure mode was obtained experimentally through the failure mode analysis. For DP590 steel sheets of 1.6mm thickness, resistance spot welds were fabricated to acquire the weld responses i.e. shear – tensile strength, coach – peel strength, average microhardness of weld nugget zone, mean dynamic contact resistance and nugget diameter. The experiments for weld fabrication were designed incorporating the face centred central composite design under response surface methodology (RSM). The response models obtained were optimized using hybrid RSM – GA technique. Further the experimental results acquired from the designed experiments were used to generate prediction models of the responses using the artificial neural network approach. Hybrid ANN – GA technique was used to obtain the optimized welding process parameters. In the end, failure analysis of the weld specimens was carried out for both shear – tensile test and coach – peel test specimen.