Combustion of pulverized coal and char particles has been studied in shock tube experiments. The gas temperature was varied between 1200-1800 K and the gas pressure was about 8 bar. Experiments involved different relative fractions of nitrogen and oxygen in the gas mixture, with particles of char and two different types of coal. In all cases, 95% of the particles had a diameter smaller than 6 mu m It has been found that coal particles combustion occurs in the reaction-controlled regime and the true reaction order is close to 0 under high oxygen partial pressure. The influence of the internal surface on combustion is found to be negligible in the case of coal and to be comparable with the influence of the external surface in the case of char. The comparison of the energy release and the burn-out shows the influence of homogeneous reactions on the combustion process.