We have studied the equilibrium and kinetics of fructose-to-glucose isomerization using a commercial immobilized glucose isomerase, Sweetzyme T(R) (from NOVO), in a packed-bed recirculation reactor which enabled us to eliminate the influence of external-mass transfer and which could function as a differential reactor when a sufficient flow rate was used. The results obtained have also been corrected with regard to the influence of internal transport in the immobilized enzyme particles. Isomerization kinetics is a pseudo first-order reversible reaction in the ranges studied : 303-333 K, pH 7.5 and 0.5 to 2.0 mol/L hexose concentrations. We compare our results with those found in the literature, and propose equations for the influence of temperature on the equilibrium and on the kinetic constants.