The reaction of dehydration of neutral glycerol to glycidol in gas phase has been studied at B3LYP/6-311G(d,p) level. Optimized geometries and vibrational frequencies have been obtained for transition states and molecular complexes appearing along the different reaction pathways. Furthermore, the theoretical rate constant and equilibrium constant over a temperature range from 700 to 2100K were also calculated using the Transition-State Theory. The calculated results indicates that the dehydration of neutral glycerol to glycidol occurs at relatively high temperatures, furthermore, the dehydration will accelerate and its yields will increase with the rising of temperature.