Thermal stability evaluation of exothermic chemical reactions is of great importance to the safer design and operation of chemical processes. Dominant reaction stoichiometries and their thermochemistry parameters are key elements in the evaluation process. Identification of significant reaction pathways under possible process conditions will lead to an understanding of the overall thermodynamic and kinetic behaviour. The kinetics of 1,3-butadiene (BD) is an excellent example of conjugated dienes that undergo addition reactions. At elevated temperatures, 1,3-butadiene monomers can dimerize exothermally, and as temperature increases, secondary exothermic reactions will take place. The very high temperature and pressure rates that these reactions can attain may lead to a reaction runaway or even a thermal explosion. BD is a vapor at ambient conditions, usually stored as a pressurized liquid, and is a carcinogen, so the experimental evaluation is potentially difficult and hazardous. In this paper, the thermal stability of BD is evaluated. Dimerization and other secondary reactions are investigated by experimental thermal analysis using an automatic pressure adiabatic calorimeter (APTAC(TM)), by theoretical computational quantum chemistry methods, and empirical thermodynamic-energy correlations. A theoretical approach is conducted to predict some of the BD reaction behaviour. Results are compared to other literature data obtained using different experimental methods. (C) 2004 Elsevier B.V. All rights reserved.