In this work it is reported a detailed investigation of the effect of different production protocols based on alkaline ethanolysis on conversion yield of forage turnip, soybean, sunflower, and castor oil into the respective biodiesel. Parameters such as catalyst contents, reaction times and temperatures were evaluated. Additionally, it was also investigated the relationship between the conversion yield and the chemical composition of the fatty acids in the feedstock. Conversion yields ranging between 70% and 100% point out the viability of the production of biodiesel using ethanol. Based on thermal analysis, sequential steps of weight loss were observed indicating that biodiesel undergoes oxidative thermal decomposition with the elimination of different portions of the molecules in each step. Besides, the energies released by the samples during thermal decomposition were determined. (C) 2010 Elsevier Ltd. All rights reserved.