Synthesis of biodiesel from lard was carried out using potassium hydroxide as a catalyst. A 3 2 factorial design of experiments was used. The effects of agitation speed and catalyst concentration were studied. A regression model was obtained to predict the methyl ester concentration and adequately describe the experimental range studied. According to this study, the most suitable operational conditions were an agitation speed of 600 rpm, and 0.9 wt.% catalyst concentration. Furthermore, the product characterization was set out to meet the requirements laid down by the European Standard for biodiesel fuel (EN 14214). (C) 2009 Elsevier B.V. All rights reserved.