Underground coal gasification is an attractive option to recover energy from thin deep-lying coal seams. By injecting air into the coal layer, combustible gases are formed underground that can be used to produce energy at the surface. The principal aim of this study was to understand and describe the transport processes that determine the behaviour of the gasification process. A number of simulation models are developed based on transport equations for mass, momentum, energy and chemical species. The transport equations are discretized by using a finite-volume method. A two-dimensional version of Hottel＇s zone method has been developed to describe radiative heat transfer.