A numerical simulation of nitrogen sorption in materials with cylindrical mesopores is proposed. Multilayer formation and capillary condensation-evaporation processes are followed by using the Sonwane and Bhatia's molecular-continuum model, although an empirical expression is used to represent the potential interaction between the adsorbate and the adsorbent. The pore structure of the solid is generated by inscribing 3D cylindrical pores in a 2D square lattice. The connectivity effects on the nitrogen isotherms are studied by using percolation theory. The ability to predict the multilayer thickness and the relative pressure at which phase transition takes place is corroborated with data reported in literature, finding good fittings in this work. On the other hand, we report for the first time a study on the effect that both pore mean diameter and connectivity have on the extent of hysteresis. (c) 2006 Elsevier Ltd. All rights reserved.