Hydrated electrons and hydrogen atoms react with pentafluorophenol (PFP) to result in fluoride ion elimination and subsequent production of the tetrafluorophenoxyl radical. Evidence for the formation of this radical was obtained from its reaction with ascorbate, which is oxidized by this species as it is oxidized by other phenoxyl radicals. Tetrafluorophenoxyl radical reacts with OH- to eliminate another fluoride ion and yield the trifluorobenzosemiquinone radical anion. Addition of OH to PFP also leads to fluoride ion elimination to yield the tetrafluorobenzosemiquinone radical anion. Oxidation of PFP by SO4.- or N-3(.) yields the pentafluorophenoxyl radical.