Significant temperature gradients may exist in packed bed adsorbers due to the exothermic heat of adsorption. In this study we investigate temperature fields in a narrow tubular packed bed adsorber having tube to particle size ratio <10. Theoretical calculations are carried out using lattice Boltzmann methods (LBM) to simulate three-dimensional concentration and temperature profiles in macro- as well as micro-pores of the adsorption bed. Model simulation results show non-uniform temperature gradients across the tube's cross-section. Zones of significantly high temperature are observed within macro-voids. Temperature gradient is found to be primarily dependent on the amount of heat released, internal BET surface area, and hydrodynamic conditions prevailing in the adsorber. Agreement between the model results and the experimental data obtained with the aid of the tomography technique for a tubular adsorber is observed to be reasonable. The study is important from the point of view of a realistic design of packed bed adsorbers. (C) 2008 Elsevier Ltd. All rights reserved.