Cumene hydroperoxide (CHP) has been used as an initiator in polymerization and catalytic cleavage in the production process of phenol and acetone. It is usually produced by the cumene oxidation reaction. In its manufacturing processes, many explosion and fire incidents are caused by this material owing to its thermal instability or incompatibility in its oxidation reaction or concentrated processes. Thus, the reactive hazard on this material has to be clearly identified and its critical runaway temperature and unstable reaction criterion has to be determined. In this investigation, the critical runaway temperature and stable reaction criterion with the initial concentrations of 15 wt% and 20 wt% CHP in its reaction processes were evaluated from their reaction kinetic parameters. The results are important and useful in the production, transportation and storage processes of CHP. (C) 2001 Elsevier Science Ltd, All rights reserved.