Aluminium alloys which exhibits very attractive mechanical, physical and chemical properties have intensive demand in various areas especially marine structure. In order to join aluminium alloys various welding methods are employed but the recent innovative and environmental friendly techniques is friction stir welding. In this study dissimilar aluminium alloys AA 5383 and AA7075 have been joined using friction stir welding. The factors which influencing the welding parameter are tool rotation speed, transverse feed which are varied to 700, 800, 900 rpm and 40, 60, 80 mm/min. The 6mm plates are joined by keeping the axial force constant at 10kN. The weldment is achieved using a square tool of pin diameter 8mm. The effect of welding parameters chosen are evaluated using hardness testing to know the resistance to wear of the weld metal and tensile testing to know the properties and ductility of a weldment. The maximum tensile strength obtained is for the parameter of 700 rpm and 40 mm/min transverse feed produced a high tensile strength of 211MPa. © 2006-2015 Asian Research Publishing Network (ARPN).