In the present work, attention has been paid to the modeling of the pressure equalization step of pressure swing adsorption cycles. A reliable value of the equilibrium pressure P-eg obtained when connecting two adsorption beds is important in modeling pressure swing adsorption cycles so as to assess accurately their performances. It is shown that in some simple cases the pressure equalization step can be decomposed in independent pressurization and depressurization steps with constant pressure at the open end. This constant pressure of the pressurized or depressurized bed should be either accurately estimated or obtained experimentally prior to this decomposition. In this way, considerable savings in computation time could be obtained. However, if one wants to obtain accurate simulations for more complicated cases of real PSA processes, decomposing the equalization step into two separate steps ceases to be valid and the simultaneous simulation of the two adsorption beds is inevitable. In fact, the rough approximations usually considered in order to evaluate the equilibrium pressure would inevitably lead to erroneous values. (C) 2009 Elsevier B.V. All rights reserved.