Substituted phenylperoxyl radicals (XC(6)H(4)OO(.)) were produced from 4-bromoanisole, 4-bromophenol, and 4-bromo-N,N-dimethylaniline (XC(6)H(4)Br) in irradiated aqueous alcohol solutions. The process Involves reductive debromination of these compounds by reaction with solvated electrons and subsequent reaction of the substituted phenyl radicals (XC(6)H(4)(.)) With O-2. The rate constants for reaction of 4-MeOC(6)H(4) with O-2 and with several alcohols and for reactions of 4-MeOC(6)H(4)OO(.) with various reductants were determined. The 4-MeOC(6)H(4)OO(.) radical decays with a second-order rate law and partially yields the 4-MeOC(6)H(4)O(.) radical. On the other hand, 4-HOC6H4OO. undergoes an intramolecular electron transfer, through its deprotonated form, (OC6H4OO.)-O--, to yield the 4-HOOC6H4O. radical. Me(2)NC(6)H(4)OO(.) undergoes both intramolecular transformation and radical-radical processes, but its protonated form, Me(2)HN(+)C(6)H(4)OO(.), undergoes mainly radical-radical reactions.