An integrated system consisting of a packed bed microbioreactor and a miniaturized separator was developed for performing biocatalytic reactions in an ionic liquid medium in continuous mode. Immobilized lipase B from Candida antarctica was used as a catalyst for butyl butyrate synthesis in I [bmpy][Tf2N], which was initially selected among various commercial ionic liquids and was proven to provide good enzyme activity and stability. The microbioreactor enabled 100% conversion of 0.5 M equimolar concentration of both substrates in the chosen ionic liquid within 5 min at 25 degrees C. A mathematical model considering Ping Pong Bi Bi enzyme kinetics with inhibition by both substrates was developed to describe the microbioreactor performance. Consecutive separation of butyl butyrate with 90% efficiency was achieved in the developed miniaturized separator based on the high difference in the boiling point of products regarding the ionic liquid medium. The process set-up successfully exploits the benefits of process intensification along with the integration of processes enabling ionic liquid recycling and is, regarding its easy handling, perfectly suited for enzyme process development at the microscale. (C) 2012 Elsevier B.V. All rights reserved.