Molecular dynamics simulation was performed to study the intercalation of dimethyl sulphoxide (DMSO) in kaolinite at 300 K. Our results indicate that the simulated basal distances d(0 0 1) is in good agreement with experimental data. As the stoichiometric ratio x from 0.19 to 1.56, the intercalation of DMSO undergoes three regions. It is observed that the total potential energy of simulation system shows a sudden jump in the transition region. It suggests that DMSO/kaolinite system should overcome a barrier of potential energy if a double of DMSO layers are inserted into two clay sheets. (c) 2005 Elsevier B.V. All rights reserved.