Hydration of propylene has been studied in both liquid phase conditions and above the critical temperature and pressure of propylene. There is a significant rise in initial rate while switching over from sub-critical to supercritical conditions, mainly because of the increase in solubility of propylene in water. Substantial amount of isopropanol exists in the supercritical phase. This suggests the possibility of the enhancement in equilibrium conversion under supercritical conditions. The reaction pressure has negligible effect on reaction kinetics under these conditions (40-80 atm; temperature 373-393 K).