The mathematical model for the thermal decomposition of coal developed by Merrick has been applied to different Colombian coals. The influence of the reaction parameters, time and temperature, in relation to the mass fraction release of different volatile constituents (such as methane), was studied during devolatilization reactions. The model was applied to Colombian coals from the regions of Caldas, Antioquia, Cundinamarca, Valle del Cauca, Cerrejon, and Boyaca. Changes in the release of different compounds were observed with changing temperature in relation to the composition of the coal. It was concluded from the results that the release profile of each volatile compound, as well as the quantity produced, depended primarily on the origin of the coal, on its composition, and on the activation energy.