Temperature-programmed combustion profiles of coals and their maceral group concentrates were obtained by thermogravimetric analysis in air at a heating rate of 15 K min(-1). The maceral group concentrates were prepared by density separation of demineralized, micronized coal samples. Particle size had a significant effect on combustion profiles, with increased complexity in terms of the number of peaks observed for micronized coal compared with larger size fractions. Analysis of the combustion profiles of macerals and reconstructed whole coals indicated that in some cases maceral interactions can occur, especially in the presence of liptinite. It was also found that the reactivity of a coal cannot be predicted from the reactivities of its maceral components.