Adsorption and desorption isotherms, adsorption kinetics and TG (thermogravimetry) curves of cyclopentane, cyclohexane, benzene, and p-xylene in silicalite-1 have been measured by using intelligent gravimetric analyzer (IGA). The thermodynamic and kinetic properties of the systems, such as the heats of sorption, free energies of sorption, entropy changes, and the diffusion coefficients, have been derived from these measurements. The results suggest that the size and configuration of sorbate molecules play a critical role on the adsorption and diffusion behaviour of the systems. Tiny changes in the size and the shape of sorbate molecules can result in a significant difference in the adsorption properties. (c) 2005 Elsevier B.V. All rights reserved.