This paper describes an experimental and analytical study on the rapid devolatilization of pulverized bituminous coal injected and entrained in hot combustion gases flowing in a constant cross-section gasifier. Data on the weight loss through rapid pyrolysis, on the temperature of the heterogeneous medium, and on the composition of the overall products are correlated with an analytical model incorporating two volatile-producing competitive first-order Arrhenius reactions followed by cracking of the volatiles. The experimental parameters are the mass fraction of coal fed into the combustion gases (0 to 0. 12), the input gas temperature (1800 degree K to 2250 degree K), three particle size distributions for the same type of coal, and the residence time in the gasifier (7 to 70 ms). All data pertain to tests conducted at a pressure of one atm.