Centrifugal adsorption technology (CAT) is a new method for continuous adsorption and ion exchange involving countercurrent flow of liquid and micrometer-range adsorbent particles under the influence of a centrifugal force. Due to the fast adsorption kinetics associated with very small particles, CAT leads to extremely compact separation equipment with high capacities and excellent mass-transfer efficiencies. Experimental results on the hydrodynamics of countercurrent flow of solids and liquid in a centrifugal field are discussed in terms of flooding conditions, pressure drops and holdup of the adsorbent particles in the contactor. A model developed based on the relations for homogeneous fluidization under gravity correctly describes countercurrent flow under gravity, but does not correctly describe countercurrent flow in a centrifugal field. In general, observed capacities of this model are higher than estimated. Although the centrifugal force magnifies the apparent density difference between the two phases, the two-phase flow did not seem to exhibit heterogeneous behavior, such as observed in gas-fluidized beds.