The novel microemulsion based organogel (MBG) prepared with cationic surfactant hexadecyltrimethylammonium bromide (CTAB) was used as support for the immobilization of lipase from Candida rugosa. In this study, we found that lipase entrapped in this system is able to catalyze the esterification reaction of pentanol with caprylic acid in hexane. The maximal pentyl caprilate production of about 94% was reached in about 215 h. Recycling the immobilized enzyme was shown to be feasible, demonstrating that lipase retains its activity for several cycles. Remarkably, the enzymatic activity of lipase immobilized in the cationic MBG remained almost stable at 30 degrees C for at least 2 months. Since highly reproducible results and quantitative production of pentyl caprylate was obtained at low costs, our data suggest that the novel CTAB microemulsion based gel represents a reliable tool for biotechnological applications and a commercially attractive system. The devised matrix may be generally applicable to other biologically interesting reaction systems, i.e. to bioconversion processes in organic solvents. (C) 2005 Elsevier Ltd. All rights reserved.