The kinetics of the simultaneous isomerization and hydrogenation of glucose are studied, and the experimental results are described with a simplified reaction model. By simulating the course of the reactions with a computer the rate constants were determined, and the energies of activation were calculated. From an Arrhenius plot the apparent isomerization activation energies were deduced. Under the experimental conditions a yield of 27% mannitol was obtained starting from glucose. Higher yields can be obtained at low temperatures and low catalyst concentrations.