Optically active (R)-a-monobenzoyl glycerol (MBG) was synthesized by Candida antarctica lipase B (CHIRAZYMET L-2) catalyzed asymmetric esterification of glycerol with benzoic anhydride in organic solvents. Various conditions, such as the type and composition of the organic solvent, water content of the system, reaction temperature, and concentrations of the substrates were systematically examined and optimized in screw-capped test tubes with respect to both the reaction rate and the enzyme selectivity. 1,4-Dioxane was found to be the best solvent and no additional water was needed for the system. The optimum temperature was around 30℃, while the most suitable substrate concentrations were 100mM each for glycerol and benzoic anhydride, respectively. However, when excessive anhydride (e.g., 200mM) was used, the produced MBG could be further transformed into 1,3-dibenzoyl glycerol (DBG) by the same enzyme with a priority to (S)-MBG, resulting in a significant improvement of the product optical purity from ca. 50-70% e.e. Under optimal conditions (100mM glycerol, 100-200mM benzoic anhydride, dioxane, 25-30℃), the enzymatic synthesis of (R)-MBG was successfully operated in a packed-bed reactor for about 1 week, with an average productivity of 0.79g MBG/day/g biocatalyst in the case of continuous operation and 0.94g MBG/day/g biocatalyst in the case of semicontinuous operation. After refinement and preferential crystallization of the crude product, (R)-MBG could be obtained in an almost optically pure form (>98% e.e.).