We have compared the concentration-dependent transport diffusivity of ethane in silicalite at 300 K using neutron scattering experiments and molecular dynamics simulations. These two methods give results that are in very good quantitative agreement. The corrected diffusivity of ethane in silicalite decreases strongly with increasing loading, in marked contrast to the behavior of methane under the same conditions. At high loadings, the ethane diffusivities exhibit non-monotonicity that is related to the existence of an inflection point in the adsorption isotherm. (c) 2005 Elsevier B.V. All rights reserved.