In the recently developed hybrid welding process, a laser and an electric arc are coupled in order to combine the positive aspects of each technology: high speed, low thermal load and high seam depth, all typical features of the laser; low cost and ability to withstand bad edge preparation, typical of the MIG arc welding. In particular the exploitation of this joining technique on light alloys is a very important topic to deal with for the modern industry. This paper investigates the stability condition of a hybrid CO2-MIG welding process, by analyzing the influence of several process parameters related to the mutual position between the two heat sources. A preliminary set of experiments was carried out in order to determine the optimal distance between the laser beam and the electric arc. A second set of experiments allowed then to investigate the importance of the laser beam focal position with respect to the upper base metal surface. The welding specimens were obtained on Aluminium 6082-T6 series alloys and the depths, widths and quality of the weld beads were analyzed by means of a statistical approach and related to process parameters.