Dextransucrase catalyses the formation of dextran, but also of numerous oligosaccharides from sucrose and different accepters, if appropriate conditions are chosen. Much experimental work has been carried out and a scheme of reactions and a mathematical model have been developed to describe the complex kinetic behaviour of the enzyme. A computer program was used to calculate the parameters of the model from a broad range of experimental data, investigating a large number of kinetic tests with the accepters maltose and fructose. The results lead to design considerations for a continuous reactor system with immobilized dextransucrase to produce leucrose, a disaccharide of industrial interest.