An experimental procedure to measure the adsorption and desorption kinetics of hydrocarbons in fluid catalytic cracking (FCC) catalysts using a tapered element oscillating microbalance is described. It enables adsorption rates to be measured on a timescale of about 1 s. Experiments using n-hexane, n-heptane, n-octane, toluene and p-xylene were performed on both a commercial FCC catalyst and a pure rare-earth exchanged zeolite Y sample under non-reacting conditions (temperatures of 373-473 K). Heats of adsorption for these hydrocarbons are reported. The overall adsorption and desorption kinetics are found to depend on carrier gas flowrate in cases when adsorption is strong indicating that the length of the catalyst bed can have a significant influence on the observed kinetics. However, at high carrier gas flowrates the overall adsorption and desorption kinetics do not depend on the amount of catalyst present. It is found that the rates of adsorption and desorption of the hydrocarbons studied are the same for the FCC catalyst as for the pure zeolite Y sample. This means that mass transport in the matrix component of the FCC catalyst is rapid and not a limiting step in the adsorption process for the hydrocarbons studied in this work. (C) 2004 Elsevier Ltd. All rights reserved.