Abstract In view of the well-known embrittlement associated with welded Al-Cu joints, a low temperature friction welding process for joining aluminum to copper has been considered. This process is characterized by the joint action of a lower rotating speed and a moderately high axial welding pressure so as to keep the temperature by friction at the weld interface never raised above that of the eutectic point (548℃) in Al-Cu system, and at the same time to obtain a sufficient plastic de-formation at the friction surfaces of the joint. As a result, the many unsatisfactory features such as low mechanical strength and poor toughness of the weld joint generally associated with the conventional friction welding for dissimilar metals were much improved. Tests for hot stability, aging properties and practical applications also proved that the joint quality fully satisfied the technical requirements.