Product energy distributions (PEDs) were computed on the four-center HF elimination from 1,1-difluoroethylene by using direct trajectory calculations. The vibrational and rotational populations of HF obtained with a quasi-classical normal mode/rigid rotor excitation model compare very well with the experimental results. Also, the translational energy distributions obtained with an efficient microcanonical sampling (EMS) at the barrier are in excellent accord with experiment and do not substantially change as the excitation energy increases.