The temperature dependance of the reaction of levansucrase with sucrose was studied, and the variation of the equilibrium constants of the Michaelis and acceptor reaction, and the maximum velocities for all three parallel reactions (levan formation, inversion and oligosaccharide formation) have been determined. The activation energies of these three reactions were evaluated. The following values were found: oligosaccharide formation 22, inversion 8, levan formation below 24°C 7 and above this temperature 0.7 kcal/Mol. The abnormal behaviour of the levan formation could be interpreted by assuming that different subreactions proceed simultanously, and the one which ends last determines the temperature dependance. More detailed ideas of the nature of these subreactions are presented. This new reaction mechanism must be distinguished from the consecutive reaction mechanism in which different subreactions follow each other. Together with the reaction mechanism as evaluated in an earlier paper, a hypothetical model of the course of the total reaction at the active site of the enzyme has been proposed.