The finite nature of fossil fuel necessitates consideration of alternative fuel from renewable sources. Palm kernel oil (PKO) has been identified as a renewable resource from which biodiesel can be produced. The effect of ethanol-PKO ratio on PKO biodiesel yield was studied with a view to obtaining optimal feedstock ratio. Experiments were conducted for ethanol-PKO ratios 0.1, 0.125, 0.15, 0.175, 0.2, 0.225 and 0.25 under transesterification conditions of 60 degrees C temperature, 120 min reaction time and 1.0% KOH catalyst concentration. Results obtained gave 29.5%, 54%, 75%, 89%, 96%, 93.5% and 87.2% average PKO biodiesel yield for the respective feedstock ratios. This shows increase in biodiesel yield with ethanol-PKO ratio up to 0.2. Standard fuel test results of the PKO biodiesel are within biodiesel specifications. (C) 2007 Elsevier Ltd. All rights reserved.