Covalent organic frameworks (COF) are nano porous structures constructed solely from strong covalent bonds. Due to the high thermal stability, very low density and high surface area, they generate significant interest for their potential application as hydrogen storage materials. Molecular dynamics simulations were applied to check the stability of COFs under hydrogen pressure and to determine the position of preferential hydrogen sites in 2D and 3D COFs. We find that the most favoured adsorption site of H-2 is on benzene rings in the organic linkers as well as the H-2 can adsorb near boron-oxygen networks. The adsorption interaction energy for COFs is found to be similar to 3.0 kJ/mol. (C) 2010 Elsevier B.V. All rights reserved.