ABSTRACTBiodiesel production in Brazil is expected to increase significantly over the coming years as there is a government plan to increase the percentage of biodiesel in diesel. With the new Brazilian energy matrix it becomes increasingly necessary to know the behavior of metallic materials used in transport and storage systems of new fuels in particular of biodiesel. The corrosiveness of traditional fuels against the structural metallic materials is well known both in the pipeline and storage tank systems which still does not occur with biodiesel. In this study the corrosiveness of biodiesel obtained from bovine fat soybean and castor oil against carbon steel ASTM A 36 and austenitic stainless steel AISI 316 was evaluated through gravimetric corrosion tests at different temperatures at three different moisture levels and in closed and open environments. Stainless steel was also studied after sensitization heat treatment to simulate possible changes in microstructure due to welding operations. As the number of variables involved in the study was very large a statistical design of experiments was adopted which reduced by 50% the amount of tests. This paper describes the adopted test methodologies the obtained results and the discussion of the influence of the tested variables on the corrosion processes. The corrosiveness of the three types of biodiesel was also verified after aging for 60 days and 120 days. The results showed no significant change in the corrosiveness of either biodiesel as a function of aging time. Testing was also performed according to the NACE TM 0172 standard test method which indicates a corrosion inhibition effect of biodiesel from castor beans. Keywords: biodiesel corrosiveness carbon steel stainless steel