The novel approach of the present work is the investigation of mechanical and metallurgical performance characteristics of two aluminium alloy 5052-H32 and 5053-H11 joint welded by friction stir welding. The experimental dissimilar metal friction stir welding investigated the influencing input welding process parameters and resultant effects on the performance characteristics of the welded specimen. The square pin tool with 15 mm tool shoulder diameter and a constant tool feed of 28 mm/min was used with varying tool rotation speed of 800, 1000 and 1200 rpm in conjunction with 10kN axial thrust were utilized in experimentally producing dissimilar weld joints. The welded specimen were subsequently characterized for microstructural, tensile strength and microhardness properties by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, tensile test and Vickers microhardness survey. Improved grain structure and reduced defects and dislocations were observed with specimen welded by 1000rpm tool rotational speed with 87.67% joint efficiency with 13.29% elongation. The influencing parameters was identified to be tool rotational speed contributing significantly in improving microhardness of the specimen by 12.86% over the base aluminium 5083-H32 alloy

Keywords: Friction stir welding, Dissimilar joints, Microstructure analysis, Mechanical behaviour