This paper deals with the hydraulics of a rotating contactor containing high density structured packing. Such a contactor can be used for distillation, absorption or stripping. Flood point data have been obtained from a contactor using air and water as working fluids. The results are well correlated using Wallis’ equation for two-phase countercurrent flow. The predicted effects of acceleration and packing specific surface area on flooding are confirmed by experimental data. The resulting equation which describes flooding can be rearranged to give flooding lines on a Sherwood type plot for conventional vertical non-rotating columns containing structured packing. The predicted flooding line for Mellapak 250Y closely matches Billet’s published data. This work provides further evidence that a Wallis-type plot is a better way to correlate structured packing flooding data than the more usual Sherwood-type plot for both rotating, and conventional vertical non-rotating, packed columns.