A serious upset in process conditions may result in a Reactive Chemicals incident. in such an emergency, procedures must be implemented to prevent injuries, mitigate the event and minimize property loss and/or environmental release as dictated by the required facility Emergency Plan. This article describes the process the Dow Chemical Company uses for engaging Reactive Chemicals experts in an emergency situation. in order to be effective, the Reactive Chemicals expert must have or be provided with in-depth knowledge of the process streams and raw materials involved. The information is crucial for understanding what is happening, what might happen in the immediate future, and what can be done to successfully mitigate the Reactive Chemicals incident. Following the incident, calorimetric experiments are typically performed to confirm or refute the hypotheses of what caused the event; additionally, the experiments provide information as to reactive chemicals hazards that may potentially still exist in the process streams. The aforementioned process will be illustrated by describing an actual event. Useful methods are described and recommended for (a) characterizing and storing reactive chemicals, and (h) responding and mitigating safety incidents with reactive chemicals. The role of a reactive chemicals "expert" during and after a plant emergency is important and potentially critical to the safe handling of an ongoing event and also in determining the root cause of the incident, (C) 2009 American Institute of Chemical Engineers Process Saf Prog 29: 2-10, 2010