The model proposed here considers the physical and chemical processes occurring in a gasifying single particle and correlates the predicted results with experimental macroscopic data. An active carbon species in assumed to react in two parallel steps to form a gaseous product or stabilised char (coke). Reactant and product diffuse in and out of the particle while the local micropore structure can vary due to carbon reaction and consumption. The model permits estimation of the local radial distribution of reactant and product concentrations, reaction rates, surface areas and porosities with time. Global properties, such as product yields, surface area and porosity are also calculated, for comparison with the corresponding experimental quantities. The model is applied here to coal hydrogasification, a process which has received less attention compared with steam or CO2 gasification.