Intracrystalline concentration profiles of methanol during its adsorption into the one-dimensional channels of CrAPO-5 crystals are reported. The profiles were recorded by the interference microscopy technique recently introduced in our laboratory. The exceptionally high spatial resolution, which can be achieved by this technique allowed us to obtain detailed information on the interplay of intracrystalline diffusion, the permeability of the crystal surface and the role of the intergrowth effects on molecule uptake. Comparison of the measured concentration profiles with those simulated by the dynamic Monte Carlo method provides quantitative information on the intracrystalline diffusivity of methanol and the permeability of the transport barriers on the crystal surface. (C) 2003 American Institute of Physics.