Historically, during petroleum shortage, vegetable oils and their derivatives have been proposed as alternatives to petroleum diesel fuel. Since 1930, different approaches have been proposed by Brazilian's universities and research institutes, including the use of neat vegetable oils (pure or in blends) or their derivatives, such as hydrocarbons obtained by thermal-catalytic cracking and fatty acids' methyl or ethyl esters (nowadays known as "biodiesel") produced by alcoholysis. Recently, the external dependence on imported diesel fuel and the present petroleum crisis have increased the discussion in Brazil in the sense of starting to use alternatives to diesel fuel, biodiesel being the main alternative for a large petroleum diesel substitution program. (C) 2007 Elsevier Ltd. All rights reserved.