A mathematical model was proposed to simulate the beryllium uptake within a fixed porous flow-through reactor. The effects of various structural, kinetic and hydraulic parameters on the behavior of the flow reactor were studied. These include linear velocity of the fluid, packing density, void fraction and adsorption coefficient. The proposed mathematical model is solved analytically and its predictions were compared with experimental results. A reasonable agreement between model predictions and experimental data was obtained. The model is approved to simulate the behavior of beryllium uptake along the fixed bed reactor of Amb-IR-120 and can be easily applied to similar systems. (C) 2009 Elsevier B. V. All rights reserved.