Lipase catalyzed production of oleyl oleate, which is an analogue of jojoba oil, was carried out using oleic acid and oleyl alcohol in the solvent-free system. Novozym 435, immobilized Candida antarctica lipase, was used as a biocatalyst. Response surface methodology (RSM) based on five-level, four-variable central composite rotatable design was used to evaluate the effects of important parameters on the production of oleyl oleate. Acid/alcohol molar ratio (0.5-1.5), enzyme quantity (2-10% w/w of substrates), reaction temperature (40-60degreesC), and reaction time (30-90 min) were chosen as process variables for the optimization. Among these parameters, enzyme quantity and acid/alcohol molar ratio have significant effects compared with temperature and time on the production of oleyl oleate. Optimum conditions were found to be a acid/alcohol molar ratio of 1, enzyme quantity of 7% (w/w), reaction temperature of 51degreesC, and reaction time of 75 min. The coefficient of determination (R-2 ) for the model is 0.97. Probability value is 2.9x10(-9) (P-value<0.01). This P-value demonstrates a very high significance for the regression model. The maximum oleyl oleate concentration predicted by the equation (737 g/L) agrees well with the experimentalvalue (734 g/L) obtained from the experimental verification at the optimum values.