The kinetics of the inverse microemulsion polymerization of MADQUAT initiated with sodium metabisulfite in both batch and semicontinuous reactors was studied using reaction calorimetry. It was found that the metabisulfite was able to initiate the polymerization at low temperature (20 degrees C) and that in batch reactor the polymerization stopped well before the complete conversion of the monomer due to complete consumption of the initiator, which disappeared according to first-order kinetics. High conversions were reached in short periods of time when the initiator was continuously fed during the process. In the semi-continuous process, the transport of metabisulfite from the droplets of the initiator solution to the particles seemed to be diffusionally limited and was accelerated by the availability of the emulsifier. The polymerization rate showed a complex evolution during the process owing to the interplay between transport phenomena, polymerization and initiation rates, and nucleation rate.