Abstract: The kinetics of non-catalyzed pinacol rearrangement in high temperature liquid water was investigated at 10 MPa and temperature from 180℃ to 220℃. Rate constants were evaluated with the first-order reaction assumption. The activation energy evaluated was 176.4 kJ•mol^-1. The experimental results demonstrate that non-catalyzed pinacol rearrangement in high temperature liquid water is possible with high pinacol conversion and pinacolone yield over 80%.