Friction stir welding (FSW) is a solid-state welding technique, which two workpieces join by pressure and largeplastic deformation near their melting points. The tool offset, pin offset, and position of dissimilar alloys can highlyaffect the maximum temperature and heat distribution in FSW process. In current research, the effects of threementioned variables on the maximum temperature of FSW of AA6061 and AA5086 alloys have been investigated.In this manner, Response Surface Methodology (RSM) as an auxiliary method has been used. The results show thatpin offset is the most effective parameter affecting maximum achieved temperature. In all pin and tool offsettings,placing the harder alloy (AA6061) at advancing side results in more maximum temperature increment compared tothe case which the harder alloy is at the retreating side.