The heat and mass transfer (HMT) model for transportation process in adsorbent bed is studied in relation to heat transfer (HT) model, which is dependent on assumptions such as the conduction dominance and negligible mass transfer resistance. Two general criteria are generated by performing an order of magnitude analysis to determine when the HT model can be applied in practical situation as a good approximation in the evaluation of the temperature field as well as dimensionless uptake and the criteria are validated with the numerical results. It is seen that the criterion for conduction dominance (CRI) is usually satisfied for all practical situations, but the criterion towards negligible mass transfer resistance (CR2) turns out to be more important for the selection of an appropriate model. (C) 2003 Elsevier Ltd. All rights reserved.