A microdynamic model for the adsorption and transport of molecules in ZSM-5 and silicalite-I zeolite (structure type MFI) based on ideally localized adsorption on two types of adsorption sites arranged into a regular two-dimensional lattice is presented. The adsorbed molecules move on the lattice in accordance with Langmuir kinetics of molecular exchange between occupied and unoccupied sites. One type of adsorption sites contains the molecules of higher mobility and the other, those of lower mobility, so that an immobilization/mobilization process superimposed on diffusion is described. The model is applied to treat the dynamics of a system comprising a mixture of labeled and unlabeled molecular species. The discontinuous kinetic model so obtained is transformed into a system of partial differential equations which express a continuous model of the system. The consistency of the continuous model with that based on irreversible thermodynamics is proved and the phenomenological coefficients are expressed in terms of kinetic and equilibrium parameters. It is shown that the Onsager reciprocal relation for the phenomenological cross-coefficients that expresses the coupling between the fluxes of labeled and unlabeled molecules is fulfilled. Moreover, these coefficients vanish, which implies that these processes are uncoupled in a thermodynamic sense. For an equilibrium exchange, the system of model equations can be simplified into a linear form. An expression for corrected diffusivity has been deduced based on kinetic arguments.