Diethyl hydroxyl amine is an efficient trap for alkyl, alkoxy, and peroxy radicals. The specific rate constant for the reaction of ethyl radicals (gas phase, 25"C), tert-butoxy radicals (benzene solution, 115"C), and poly (peroxystyryl) peroxy radicals (styrene solution, 50°C) were evaluated as 7.2 X lo5, 7.7 X lo7, and 2.9 X lo5 M-l-sec-', respectively. Several possible secondary reactions of the nitroxide radicals are discussed.