A novel concept of a liquid-liquid contact reactor, the so-called impinging stream-rotating packed bed (IS-RPB), was presented for improvement of micromixing iodide and iodate. The micromixing efficiency of IS-RPB was studied by adopting iodide-iodate reaction system. The effects of operational conditions (e. g. high gravity factor, liquid flow rate, liquid flow ratio and acid concentration) on micromixing efficiency (characterized by segregation index X-s) were investigated. In addition, the effects of different impinging distance and impinging angle on micromixing efficiency were also considered. Besides, IS, RPB and IS-RPB reactors were contrasted with micromixing characteristics in the same experimental conditions. Comparison with other mixing devices, IS-RPB reactor has better micromixing characteristics than other reactors, which has a good application prospect. (C) 2009 Elsevier B. V. All rights reserved.