Oxygen consumption of a bituminous coal was examined using the isothermal flow reactor technique. The experiments were undertaken at atmospheric pressure and at temperatures between 333 and 363 K. The gaseous oxidizing medium contained oxygen at concentrations of 10.9%, 20.9% and 39.9%. Experiments under various conditions showed that the rate of oxygen consumption of the coal decreases sharply in the first hour, followed by progressive decrease during the later time of the experiments. Analysis indicated that the Elovich equation is inapplicable to the current experimental data. Instead, it was found that an empirical equation in the form of an exponential function of the reciprocal time provides a very good fit to the experimental data. The rate of oxygen consumption can be further described as the sum of one constant and two exponential functions of time, reflecting two reaction sequences occurring in the oxidation process.