Char combustion rate in elevated pressure conditions was examined experimentally and theoretically by changing factors such as particle size, gas flow rate, and oxygen concentration. These factors were found to influence rate control regimes and change the pattern of pressure effect on rate. For instance, at same temperature, decrease in the particle size of char enhanced the effect of pressure on char combustion rate. Mass flow rate, ug rhog, or flow rate at standard temperature and pressure, u(g,o) was used to evaluate the diffusion resistance of the gas film. It was found that, char combustion rate increase with increasing ug rhog or u(g,o). Combustion rate can be expressed by using the oxygen concentration at standard temperature and pressure, C-o, or the partial pressure of oxygen, P-o2, as the gas reactant term in the rate equation. However, explanation of pressure effect on combustion rate was greatly different in both expressions.