Interactions between Rhizomucor miehei lipase and emulsion droplets were studied in oil-in-water emulsions. The emulsions were stabilised by either the cationic surfactant didodecyldimethylammonium bromide, the anionic surfactant sodium bis (2-ethylhexyl) sulfosuccinate or the non-ionic surfactant, 1-(2-ethylhexyl)-3-(2-ethylbutyl)-2-hexaethylene glycerol ether. By measuring the mobility of emulsion droplets it was shown that the lipase bound to droplets stabilized by the nonionic surfactant, but not to those stabilized by the negatively charged surfactants. It was experimentally impossible to show any adsorption of the lipase to the emulsion droplet surfaces consisting of the non-ionic surfactant. From Langmuir measurements it was decuced that the lipase adsorbed to positively but not negatively charged surfaces. Only a small change of the break point of the isotherm was observed in the non-ionic system. Eicosanoic acid disappeared from the air/water interface at pH4, when Rhizomucor miehei lipase was dissolved in teh subsolution. The lipase-catalyzed hydrolysis of the oil-soluble model substrate, o-nitrophenyl palmitate, was studied in emulsions stabilized by the different surfactants. The highest reaction rate was observed in systems with the non-ionic surfactant and also with the cationic surfactant, while in the anionic system almost no reaction was observed. In all three tests, i.e. the mobility of emulsion droplets, Langmuir measurements and enzymatic activity measurements, an increased salt concentration from 1μM to 1 mM sodium phosphate decreased the affinity of the lipase to the surfaces stabilized by the cationic surfactant. With a lipase-stabilized oil-in-water emulsion, displacement of the lipase from the emulsion droplet surface occurred with the cationic surfactant, but not with the anionic surfactant. Again with the non-ionic system, it was not possible to show any displacement of the lipase since the mobility value for the lipase system was almost the same as for the non-iopnic system. From each set of experiment it could be concluded independently that the lipase from Rhizomucor miehei prefers positively charged surfaces over negatively charged surfaces.