Enzyme catalyzed esterification reaction was carried out in single phase, oil-continuous microemulsions. The lipozyme was solubilized, along with glycerol and water, in the aqueous core of water/AOT/hydrocarbon microemulsion system. Upon addition of fatty acid, mono- and diglycerides were formed due to the esterification reaction taking place at the interface of the droplets in the microemulsion. The initial rate of conversion of oleic acid increases with oil chain length of the continuous phase whereas final conversion is maximum for hexane. The percent conversion of stearic acid is 30% whereas the percent conversion of oleic acid is 70%. The percent conversions of various fatty acids under the same continuous medium increases with chain length of fatty acids. The oleic acid/glycerol ratio is an important parameter for the optimum conversion of oleic acid into glycerides. The percent yield can be increased by subsequent addition of glycerol after equilibrium is reached. Temperature has a considerable effect on the synthesis reaction. HPLC analysis of samples from microemulsions show the presence of mono- and diglycerides. Possible mechanisms for the above mentioned effects are discussed.