Diffusion coefficients of different sugars and the sugar alcohol sorbitol have been determined by two different experimental setups: mass transfer through a flat membrane in a diffusion cell and effusion experiments with beads in a batch stirred vessel. Diffusion experiments show highly consistent data with low uncertainties and high regression coefficients, while effusion experiments suffer from larger experimental uncertainties. For the diffusion through a chitosan membrane at 25 degrees C, typically one-third of the free molecular diffusion coefficient is found, whereas at 40 degrees C only one-quarter of it is reached. The influence of molecular size, structure, and temperature on the transport properties is discussed in detail.