Friction stir welding (FSW) of AA 5052 H32 to AA 6061 T6 blanks was obtained for each thicknesses of 1 mm and 1.5 mm. Successful welds were obtained at constant tool spindle speed of 1500 rpm and two tool traverse speeds of 63 mm/min and 98 mm/min. For both thicknesses, weld produced at 63 mm/min speed gives more ductility than the weld produced at 98 mm/min. Elongation prior failure of 1.5 mm thick tailor welded blank (TWB) was found to be 47% more than that of 1 mm thickness weld. Microhardness measurement of the dissimilar welds showed lower values at heat-affected zones (HAZ) on both the sides of weld line, whereas lowest hardness value was obtained at HAZ of AA 5052. Optical microscope and energy dispersive spectroscopy (EDS) analyses on the stir zone (SZ) suggest dynamic recrystallization and finer grain size with uniform mixing at the center of SZ. Intermetallic compounds are formed during welding which plays detrimental role in the fracture strength of the joint.