Hydrodynamics and mass transfer characteristics in a cross-flow rotating packed bed (RPB) were studied. Models describing the liquid film flowing on the wire gauze packing, the liquid droplet size in the voids, the gas pressure drop, the gas pressure and velocity radial distribution and liquid flow direction have been established. Three different types of mass transfer processes in cross-flow RPB were studied. Mass transfer model was established based on surface renewal model. The calculated results agree well with that of experiments. Experiments show that : The gas flow rate can be as high as 15 m/s and even higher, therefore the diameter of RPB can be greatly reduced compared to that of counter-current RPB; For the liquid side controlling processes, the height of mass transfer unit is 2.5-4 cm, which is close to that of countercurrent flow RPB.