Thermal decomposition process of cumene hydroperoxide (CHP) in cumene has been investigated by different researchers from chemical and kinetic point of view although its reactive characteristics have not yet been fully identified. The major discrepancy in the literature data is represented by different reaction nth-order and autocatalytic kinetics suggested. In the present work CHP thermal decomposition is studied by means of isothermal experiments, adiabatic and scanning calometry on commercial hydroperoxide samples. The most simple autocatalytic scheme is adopted for the analysis of the data collected on CHP solutions in cumene at different initial concentrations (80%-30% w/w) allowing to estimate the kinetic parameters regulating the process. A characterization of the intermediate and product distribution at varying reaction time is attempted. The effect on the system reactivity of the addition of small quantities of carbinol or acetophenone or a-methylstyrene to the CHP solution in cumene is also studied. (C) 2008 American Institute of Chemical Engineers.