Kinetics on the adsorption of n-butene onto the acidic OH groups existing in the small pores of ferrierite (FER) were studied between 233 and 253 K by IR spectroscopy. The activation energies for the adsorption of l-butene and cis-2-butene were estimated as 23.3 and 28.4 kJ mol(-1), while that of trans-2-butene was not obtained due to its rapid adsorption. The activation energy for adsorption was considered to have resulted from the diffusion of n-butene molecules into the small micropores of FER. (C) 2000 Elsevier Science B.V. All rights reserved.