The Mozambique Ridge off East Africa is a large oceanic plateau with a north-south length of more than 800 km and an east-west extend between 200-400 km. The top of the plateau emerges up to 3000 m from the surrounding ocean floor of the Mozambique Basin to the east and the southern Natal Valley to the west. However, due to a lack of extensive refraction seismic profiles the internal structure and origin of the ridge is still a matter of controversial debate. The existence of a continental plateau (as proposed by many authors) east of Africa which was possibly once attached to the African continent has far reaching consequences for the opening between Africa and East Antarctica and the development of ocean currents between the Indian and South Atlantic Ocean. However, until now, plate tectonic reconstructions for the breakup of Gondwana between Africa and East Antarctica cannot integrate this continental fragment in a satisfactory way.Precise age information from the ocean floor south of the ridge and the identification of characteristic magnetic anomaly lineations on the ridge can significantly contribute to this debate. This was one of the objectives of the AISTEK-II expedition carried out from Mai to July 2005 with the German research vessel SONNE off southeast Africa and Madagascar. During this cruise, for the first time, systematic high resolution magnetic measurements were carried out in the area of the Mozambique Ridge and in the Mozambique Basin. Precise identifications of magnetic seafloor spreading anomalies could be made in the Mozambique Basin. In general, existing interpretations from various French expeditions could be confirmed, albeit the new data can extend the interpretations further west and enhance the precision of the existing anomaly picks. Thus, with the new data the seafloor spreading history between Africa and East Antarctica can be better constrained using high resolution age information for the ocean floor in the Mozambique Basin and the Riiser-Larsen Sea, Antarctica.The magnetic anomaly data from the Mozambique Ridge have large amplitudes with values of up to 800 nT. Good correlations between the lines are mainly possible at the position of the high amplitude anomalies. Although no unique identification of seafloor spreading anomalies can be made on the ridge several arguments exist in favor of an oceanic origin of this plateau.