Dielectric analysis has become an effective means of monitoring a variety of processing features for thermoset polymerizations because dielectric properties are sensitive to changes of resins properties. In the present work, dielectric analysis is used for the on-line evaluation of the overall conversion during the batch solution copolymerization of methyl methacrylate and butyl acrylate (MMA/BuA). The dielectric loss factor is empirically correlated to the overall conversion, measured off-line; and the MMA fraction of the recipe. It is shown that the technique can be used for the successful real-time evaluation of monomer conversion during radical copolymerization operations. Such in-line monitoring of the production of thermosplastic is a rather new field of application for dielectric analysis.