The paper deals with modelling of the flow of liquid on a plate with mobile packing. The results of measurements have been interpreted by means of a simple dispersion model whose two parameters were determined from the nonideal step-input of a tracer and its response. It has been found that in the gas flow rate region followed (1.0 - 3.5 m s-1), the liquid flow rate followed (5.36 - 12.5 . 10-3 m s-1), and the static bed height followed (21 - 47 . 10-3 m) the diffusion Peclet number is independent of these quantities. The mean residence time of the liquid on the plate decreases with increasing flow rate of Both gas and liquid, but it increases with the increasing height of packing.