Bromine atoms produced via the 76Kr(E.C.)76 Br and the (77(γ+/E.C.)77Br nuclear transformations allowed to react with benzene in the gas, liquid, and solid phases, as well as in the presence of various non-inert chemical additives. From calculated collision cross sections, charge-exchange cross sections, and other physical arguments, it was concluded that chargetransfer neutralization of 76, 77Brn+ cations occurs faster than substitution reactions and that both decay-induced bromination mechanisms involve reactive bromine radicals. In the gas phase, the principle reaction pathway is substitution. In the liquid phase substitution yields increase and polymerization also occurs. Solid phase reactions indicate that substitution and polymerization reactions occur as well as fragmentation reactions arising from “caging” mechanisms. Chemical additives with electronic characteristics had no effect on substitution yields by nucleogenic, 76, 77Br. Chemical scavengers of bromine atoms were found to have a yield-decreasing effect.