Spot welding is the primarily applied bonding technique in the automotive industry, especially for the assembly of vehicle bodies. As up to 5000 weld spots are required to securely weld a single body, manufacturers are constantly seeking to optimize welding parameters and results. Newly developed metallic coatings on cold rolled steel sheets lead to unsatisfying welding results. Specifically, the surfaces of weld spots on zinc-magnesium (ZM) hot dip galvanized sheets show sharp spikes. These spikes can provoke irregularities during the lacquering process. Furthermore, they are visually unsatisfying, especially in the areas of the vehicle body that are visible to the customer, such as for example the doorframe. The causes behind these spikes’ formation remain unknown, though they are known to form exclusively on zinc coatings and only under a limited range of circumstances. While the new ZM coating shows many technological benefits such as better corrosion performance, its processability is limited due to the problematic surface quality of weld spots. In the frame of this thesis potential development mechanisms of the spikes were evaluated, and weld spots were examined on an optical basis by means of stereomicroscopy and scanning-electron-microscopy. Welding parameters were varied in multiple ways in order to understand their impact on the welding result. Furthermore, the influence of electrode geometry, the thickness of the ZM layer, surface lubrication, and electrode abrasion were included in a comprehensive sensitivity study.. Among all investigations, the ones focusing on temperature flow in the heat-affected zone, especially on the surface, have shown the most significant results. Spikes can only form in a specific temperature range, which was determined experimentally and respective welding parameters were found to achieve optically acceptable weld spots. The formation mechanism, based on accretion of ZM material on the electrode surface combined with liquid coating material at the time of elevation of the electrode, was examined in detail. Methods to avoid the formation of zinc spikes were developed, based on the knowledge gained about the formation mechanisms. These range from optimization of the welding parameters regarding heat input, to polishing of the electrode surface after milling and the variation of the welding sequence to lower the local heat input.