Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the three important reaction variables -methanol/oil molar ratio (x(1)), reaction time (x(2)) and amount of catalyst (x(3)) for production of biodiesel from palm oil using KF/ZnO catalyst. Based on the CCD, a quadratic model was developed to correlate the reaction variables to the biodiesel yield. From the analysis of variance (ANOVA), the most influential factor on the experimental design response was identified. The predicted yield after process optimization was found to agree satisfactory with the experimental value. The optimum conditions for biodiesel production were found as follows: methanol/oil ratio of 11.43. reaction time of 9.72 h and catalyst amount of 5.52 wt%. The optimum biodiesel yield was 89.23%. (C) 2008 Elsevier B.V. All rights reserved.