The reaction of a series of diallylamines and related compounds with free radicals in aqueous acid solution has been studied in a flow system using ESR spectroscopy. The initiation was by radicals generated from titanium trichloride-hydrogen peroxide (hydroxyl radicals) and titanium trichloride-hydroxylamine (amino radicals) systems, respectively. The observed ESR spectra were assigned to five-membered ring radicals as the major radical species present in the system. However, the dimethallyl-amine series gave both five - and six-membered ring radicals.