In the present investigation, an optimization of the friction stir spot welding (FSSW) process parameters to minimize the corrosion rate in the stirred zone (SZ) of AA1050-O/AA6061-T4 dissimilar Al lap joints carried out. The joints were welded using different tool rotational speeds, dwell times and plunging depths. Full factorial design of experiments approach has been employed to examine the influences of the aforementioned process parameters on the corrosion rate of the friction stir spot welded (FSSWed) joints. The results revealed that the optimum FSSW process parameter that minimize the corrosion rate (about 6.22×10-4 mm/year) are tool rotational speed of 1400 rpm, dwell time of 7 sec. and plunging depth of 3.05 mm .