Electronic structure calculations (MP2, B3LYP, and MC3BB) were performed to characterize the stationary points involved in the elimination of HX (X = F, Cl) from chlorofluoroethylene. The calculations predict 10 different HX elimination channels, being the HF elimination energetically favoured over the HCl elimination. The relative product abundances were computed as a function of the energy, using RRKM theory. At low energies, near threshold, the total HF/HCl ratio is greater than unity, but as the energy increases, the ratio becomes less than unity due to an entropic effect. This trend is in agreement with the experimental observations. (c) 2006 Elsevier B.V. All rights reserved.