The elimination process which occurs during the thermal degradation of poly(vinyl acetate) has been studied using thermal analysis-Fourier transform infrared spectroscopy. It was found that elimination of acetate groups initially began slowly, but increased as degradation proceeded due to an additional process. The increase in rate was found to depend on the concentration of unsaturated groups in the polymer chain. The activation energy for the initial step was found to be 190 kJ mol(-1), while that for the additional process was 130 kJ mol(-1). The additional process of elimination was considered to be, due to a four-membered transition state, activated by double bonds adjacent to the acetate unit.