Results are presented for the experimentally observed separation efficiencies obtained, under cyclic equilibrium conditions, for the removal of Freon 12 from air using small-scale beds of activated carbon operating on a simple pressure swing basis. The experimental results were simulated using an adiabatic bed model incorporating a simple linear force to represent the adsorption kinetics. By varying the effective solid phase diffusion coefficient over the relatively narrow range of 3 to 6 x 10(-11) m2/s, all the experimentally observed separation efficiencies could be reproduced other than those at the lowest cycle times investigated. The effective diffusivities given by the simulation are correlated in terms of two of the main operating parameters investigated and are compared with those obtained from microbalance studies.