This paper takes a look on the effects of mass transport limitation occurring in hydrolysis of rape seed oil by means of an interfacial activated lipase from Thermomyces lanuginosus. In order to carry out investigations for process optimization, the slug flow reactor was chosen in which a large interfacial area can be generated and the mass transport can be investigated individually for each phase. The choice of the capillary material determines the dispersed and the continuous phase. As shown by computational fluid dynamics simulation, the continuous phase is well mixed due to wall effects. The mixing patterns in the dispersed phase differ due to viscous forces between the phases. It was found that, at the same fluid velocities, the conversion in the glass capillary is higher than in the PTFE capillary. The surface-specific hydrolysis rate is used for comparison purposes, since the properties of the capillary are different. Increasing the velocity, the hydrolysis rate can be considerably increased in comparison to stagnant conditions. Already at a fluid velocity of 1 mm s(-1), the hydrolysis rates increased to 2.3-fold in the glass capillary and moreover by a factor of 4 in the PTFE capillary.