The lipase-catalyzed kinetic resolution of different 3-hydroxy esters in organic solvents and supercritical carbon dioxide (SCCO2) was studied. Similar enantiomeric excesses (ee, up to 99%) as found for transesterifications in organic solvents were achieved also in SCCO2. The influence of various reaction parameters was investigated for the resolution of 3-hydroxy octanoic acid methyl esters with lipase from Pseudomonas cepacia in SCCO2. Optimum conditions have been found at 110 bar 40 degrees C, and in the presence of 1.5 g molecular sieve by using vinyl acetate as acyl donor. The addition of different cosolvents had only a small effect on the reaction. Immobilization of the lipase on VA-epoxy resulted in similar optical purities as found for the crude lipase, but at halved reaction times. The effect of supercritical conditions on the stability of the lipase was also investigated.