The iodide/iodate chemical test reaction (named Villermaux-Dushman method) initially proposed to characterize micromixing in conventional stirred tank reactors has become an extensive method to characterize continuous micromixers. Several protocols have been proposed and adapted to very efficient devices, but misunderstanding makes the use of this chemical test somewhat difficult which can lead to erroneous results. Furthermore, many papers only present the segregation index which is very dependent of the concentration set when mixing time, a concentration-free feature, should be preferred to compare micromixers. This paper presents the detailed protocol of the iodide/iodate test method, with different concentration sets and a general protocol to determine mixing times in micromixers.