The fundamental thermal behavior of five materials (Illinois coal #6, Kentucky coal #9, polyvinyl chloride, cellulose and newspaper) has been investigated using the TGA/FTIR/MS system under different combustion conditions. At a fast heating rate, the decomposition temperatures shift towards higher temperatures and the maximum weight loss rates increase by 3-7 times those at the slow heating rate. The gases evolved from the decomposition have been analyzed kinetically. More organic compounds are identified at the faster heating rate. Also, molecular chlorine is observed in the oxidation of PVC. These two species may lead to the formation of chlorinated organic compounds. The results indicate that the TGA/FTIR/MS system can be used to evaluate the effect on the environment of co-firing high-sulfur coal with refuse-derived fuels.