This work deals with the resolution of DL-menthol with propionic acid by Candida cylindracea lipase (Ccl) in organic solvent reaction systems and a reverse micelles system of sodium 1,4-bis (2-ethylhexyl) sulfosuccinate (AOT). The activity and stability as well as enantioselectivity of the lipase in two systems were studied. The results indicate that the lipase showed higher stability in reverse micelles than in organic solvent, which proved that the reverse micelles system has potential application for maintaining the activity of the enzyme for a long time. This is because lipase molecules can be entrapped in water-containing micro-drops of reverse micelles, avoiding direct-contract with unfavorable organic medium. The enantioselectivity (E > 30, ee(p) = 92.5) in the two systems is relatively high, although the conversion is moderate. The influence of the characteristic parameters of the two systems, such as pH, temperature, w(0) (molar ratio of water to AOT in reverse micelles systems) and water content (organic solvent) on the conversion of DL-menthol was also investigated. (c) 2005 Society of Chemical Industry.