The oil from the macaúba (Acrocomia aculeata) fruit, a native palm in Brazil, has a real potential for the industrial production of biodiesel. This report describes an experimental work devoted to monitor the chemical behavior of the fatty acid methyl esters from oil of the macaúba fruit kernel and the leaching of metal elements into the biodiesel put in contact with the ASTM A283 grade C and API X65 carbon steels, used to build fuel storage tanks and biodiesel pipelines. The mean values of esters contents points that the analytical precision from atomic absorption measurements was not enough to support a statistically reliable interpretation of the chemical leaching of metals into the biodiesel; a more accurate set of data must be obtained with more sensitive chemical analytical techniques. From the Mössbauer data, the surface of the non - galvanized steels in contact with this biodiesel for up to 105 days tend to be somehow protected against most oxidative reactions even in direct contact with air, although few amount magnetite (Fe3O4) was detected.