Transesterification between triolein (OOO) and ethylbehenate (EB) was carried out to produce 1,3-dibehenoyl-2-oleoyl glycerol. (BOB), an antiblooming agent for chocolate, by 1,3-regiospecific immobilized lipase (Lipozyme IM) in supercritical carbon dioxide (SCCO2). An increase in the concentration of EB accelerated the transesterification activity to BOB while an increase in the concentration of 000 was inhibitory, suggesting that the transesterification proceeds via behenoyl-enzyme complex. The optimum water content in immobilized enzyme for transesterification increased with an increase in the initial substrate concentration. The optimum temperature and pressure for the maximum productivity of BOB were determined to be 50 degrees C and 15 MPa, respectively, as determined from both the initial period activity and the reaction equilibrium.