The decomposition of 2-isopropylphenol at temperatures of 613-713 K and water densities of 0-0.6 g/cm(3) yielded phenol, propene, and 2-propylphenol. The decomposition was determined to occur via two reaction pathways: (1) dealkylation of 2-isopropylphenol to produce phenol and propene and (2) rearrangement of the propyl functional group from 2-isopropylphenol to 2-propylphenol. The rate constant for dealkylation increased proportionally with increasing water density. The reaction rate for rearrangement was invariant with the water density. The rate constants for dealkylation and rearrangement could be correlated as a function of temperature and water density with a global reaction model.