During casting and homogenisation of aluminium the microstructural fundament for further processing is made. Particle structure (dispersoids and primary particles), grain structure and level of elements in solid solution govern the mechanical and annealing properties of the material. In 3xxx-alloys, Mn in solid solution and Mn-containing dispersoids formed during homogenisation play an important role in controlling the recrystallization behaviour of the material [e.g. 1, 2, 3]. Other elements, such as Si, will have an influence on the formation of dispersoids [4, 5]. Hence, to control the annealing behaviour of the material, it becomes important to control the particle structure. In the present investigation, an AA3103 alloy, and modified versions of this alloy, have been investigated. Various homogenisation treatments have been performed and the resulting material has been studied. Electrical conductivity has been measured and microstructural investigations have been carried out.