Friction stir welding (FSW) is a solid state welding process for joining metallic alloys and dissimilar metals. It has emerged as an alternative technology to weld high strength alloys that are difficult to join with conventional techniques. FSW is used to produce products with better mechanical properties. Nowadays aluminum alloys have been widely used in several industrial applications such as aerospace, marine, automobile and commercial applications due to their light weight structure, better mechanical properties, and corrosion resistance. In this work, three welding parameters such as spindle speed, welding speed and plunge depth were considered for friction stir welding. FSW was carried out between AA2024and AA6082 dissimilar aluminum alloy plates to produce But joint. A central composite rotatable design with three factors and five levels was chosen. The shear strength and hardness of the welded regions were evaluated.