The combustion of bed fuel in a packed bed reactor can be assumed very complicated. Researchers have studied this problem for many years. Such studies have been performed by both empirical and computational methods. However, due to the sharp increase in the development of computer science based packages, the Computational Fluid Dynamics (CFD) technique can be applied to simulate and analyse the performance of the combustion reaction. Consequently, this has saved on empirical expenditures and has additionally provided more understanding about the research objective. This paper models the computation of bed fuel combustion in a packed bed reactor using Fluent version 6.2. The User Defined Functions (UDFs) were created to define the system as well as boundary conditions, initial conditions, and dynamic mesh deforming. Furthermore, the source terms, heat exchanges and homogeneous reactions were also defined in UDFs. The species transport and volume reaction were used to model the gas phase, where the Eulerian model was employed to solve the problem using two phase modelling. The k-e sub-model was employed for turbulence, together with an unsteady model, as the problem was regarded as being unstable. The results obtained from the modelling work would give more understanding about the bed fuel combustion in packed bed reactor.