Due to the coupled filler material and energy supply in GMAW processes, these processes have limited productivity. To increase productivity and decrease heat input, conventional GMAW processes can be combined with an auxiliary hot wire. In this paper a GMAW hot wire process with indirect resistive heating of the auxiliary wire (between two current nozzles) is used for joint welding of thick sheets (mild steel). In order to demonstrate the potential of the process for joint welding of mild steel plates (8 mm and 20 mm), test welds are carried out. The welding samples are then separated and the internal seam properties determined. In addition, Charpy impact and tensile specimens are produced to determine the mechanical properties of the joint. To further increase the understanding of the process, calorimetric measurements are conducted to quantify the energy input of the process into the substrate. Based on the performed analyses, it is possible to demonstrate the potential of the process for joint welding and to show a possible competition to existing processes.