The activity of Chromobacterium viscosum lipase for hydrolysis of olive oil in sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles was increased by pretreatment with acetone. In contrast to the untreated lipase, no sharp fall in the activity of the treated lipase at higher W-0 (water to AOT molar ratio) values was observed. The fluorescence emission intensity of the treated lipase in reverse micelles was higher than that of the untreated lipase but the maximal emission wavelength (lambda(max)) was the same for both lipases. A kinetic model that considers the free substrate in equilibrium with the substrate adsorbed on the micellar surface was successfully used to better understand the activity enhancement. The Michaelis constant (K-m) and substrate adsorption equilibrium constant (K-ad) were reduced by lipase pretreatment with acetone whereas the maximum reaction rate (v(max)) remained unaltered. (c) 2005 Society of Chemical Industry.