AbstractThe dispersion coefficient is evaluated in a general linear chromatographic system in which the velocity field is time periodic. Computations are carried out in detail for two examples. In the first example there are two phases and the flow pattern is simple. In the second example there is only one phase and the flow pattern is complex. The latter example is closely related to Taylor diffusion. Depending on the relative size of certain dimensionless parameters, one can distinguish four regions of different qualitative behavior of the system: molecular diffusion region, Taylor region, constant amplification region, and boundary transport region.