To increase its capacity, a production plant investigated raising the operating temperature of a wiped-film evaporator (WFE) unit. The WFE separates a high-boiling product (taken overhead) from a heavy tar stream (taken out the bottom). Both product and tars begin to decompose at temperatures near the operating temperature of the WFE. The plant's Management of Change procedure required that all potential reactivity hazards be considered before making the proposed change. This paper describes the experimental work done on plant samples with ARC and Setaram C-80 instruments, and how decomposition kinetic parameters were estimated using thermal safety software from Cheminform St. Petersburg, Ltd. The results of this hazard evaluation allowed the plant personnel to make an informed decision about the proposed operating change.