The activity of lipase-catalysed hydrolysis of olive oil in SDS-1-butanol-olive oil-water microemulsions was investigated. The kinetics of lipases in reverse microemulsions and water were also compared. The influences of the characteristic parameters of these systems, such as pH, temperature (T), molar ratio ((o)) of water to SDS, the concentrations of enzyme and substrate, on the activity of an enzyme were examined. According to the optimum conditions the production and activity were measured at pH=4, T=40 degrees C, (o)=12. The activation energy of the reaction was calculated from the Arrhenius plot. It was found that the hydrolysis reaction obeyed Michaelis-Menten kinetics and the apparent Michaelis K-m,K-a and the apparent maximal reaction rate V-max were determined. The effect of microemulsion's surfactant (SDS) on enzymatic activity was also discussed.