Nitroxide-terminated polystyrenes resulting from "living" free radical polymerization processes have been "functionalized" by combination reaction with thiuram disulfide compounds, i.e., tetraethyl thiuram disulfide (3a), and N,N＇-diethyl-N,N＇-bis{2-((trimethylsilyl)oxy)ethyl} thiuram disulfide (3c). The quantitative substitution of the nitroxide moiety by the dithiocarbamate group has been characterized by H-1 NMR, C-13 NMR, and IR spectroscopy, MALDI-TOF mass spectrometry, ESI mass spectrometry, and LSI mass spectrometry. The reaction has also been studied on a model compound.