Quasielastic neutron scattering (QENS) was used to investigate the diffusion of propane in zeolite ZSM-5 under static and macroscopic flow conditions. The rate of self-diffusion in the adsorbed phase was slightly faster under the flow conditions studied. Control measurements showed that the broadening seen in the quasielastic signal must result from propane condensed in the zeolitic pore and not from gas, either in the bulk or inter-particle voids. Crown Copyright (C) 2018 Published by Elsevier Ltd. All rights reserved.