A TG/FTIR system was used to identify the products of thermal oxidative degradation of PVB, and also to elucidate the mechanism of degradation. This technique is useful in the kinetic analysis of fast reactions such as polymer degradation, unlike the use of a TG/GC/FTIR system, In which long retention times are needed to separate the products. A computer resolution method based on a pattern recognition technique is proposed to resolve the dynamic mixture IR spectra of the degradation products. A four-component synthetic mixture was used to evaluate the performance of the resolution algorithm and was found to be accurate within +/-5%. The method was then applied to PVB degradation. The dynamic information of PVB thermal oxidative degradation obtained by resolving the mixture IR spectra was used to elucidate the reaction mechanism and to determine the kinetic parameters. Results showed that PVB degradation in air took place at a temperature 50K lower and the overall activation energy dropped from 338 kJ/mole (in nitrogen) to 200 kJ/mole (in air) compared with the degradation in a nitrogen atmosphere.