15This review paper describes the state-of-the-art in the field of HiGee contactors used for gas-16 liquid mass transfer processes, with a special focus on distillation, and for heterogeneously 17 catalyzed reactions. 18Several types of rotating beds are discussed, including single-block rotating packed-bed, split-19 packing rotating bed, rotating zigzag bed, two-stage counter-current rotating packed bed, 20 blade packing rotating packed bed, rotating bed with blade packing and baffles, counter-flow 21 concentric-ring rotating bed and crossflow concentric-baffle rotating bed. 22The working principles of HiGee technology, as well as the modeling, design and control 23 aspects, and practical applications are explained and discussed. In addition, this paper 24 addresses the advantages and disadvantages with respect to mass-transfer performance, 25 pressure drop, rotor complexity and suitability to perform continuous distillation and to be 26