Micromixing efficiency of viscous media in novel IS-RPB reactor was studied by using iodide-iodate test reaction as working system. Experiments were carried out in glycerol-water solution with different viscosities. The effects of high gravity factor, liquid flow rate, acid concentration, liquid flow ratio, and viscosity on segregation index and micromixing time were investigated. The experimental results showed that the IS-RPB was effective in enhancing micrombdng when the liquid viscosity increased. Furthermore, the micromixing time t(m) of the IS-RPB reactor was determined based on the incorporation model, and its value was in the range of 10(-5)-10(-4) s. Compared with other mixing devices, IS-RPB reactor has better micromixing characteristics than other reactors, which has a good application prospect.