9-Anthroyloxyl radicals are generated from photocleavage of the N-O bond of N-(9-anthroyloxy)-9-fluorenylideneamine and 1-(9-anthroyloxy)-2-pyridone in acetonitrile. They are much less reactive in decarboxylation, addition to olefins, and hydrogen-atom abstraction than benzoyloxyl and 1-naphthoyl-oxyl radicals, and supposedly undergo intramolecular addition to the ipso position to give alpha -lactonic spiroanthracenyl radicals.