Lipase from Candida cylindracea was immobilized in the gel beads prepared by copolymerization of N-isopropylacrylamide, N,N＇-methylenebisacrylamide, and acrylamide. The optimal conditions of immobilization of lipase, for example molar ratio of monomer, cross-linking reagent, polymerization initiator, and stirring speed, are investigated. The esterification reaction between oleic acid and glycerol was carried out at 37 degrees C by using the immobilized lipase or free lipase. It is found that selectivity of monoolein synthesis is higher when using immobilized lipase in gels compared with free lipase. The gel beads undergo thermal phase transition. The gel swells below lower critical solution temperature (LCST) and shrinks above LCST. An esterification reaction by lipase immobilized in gel was carried out by swinging the temperature between 37 degrees C (above LCST) and 5 degrees C (below LCST). It is found that the mass transfer rate in the gel is enhanced by phase transition.