are closely related to phenoxy radicals but have a unique structural feature in that they are radical anions, will be mentioned only briefly. The chemistry of semiquinones has been the subject of an earlier review paper (202; for recent references cf. 58, 208, 313). Stable radicals based on polynuclear phenols (such as naphthols etc.) will be discussed.Electron spin resonance spectroscopy has contributed more than any other tool to the structural analysis of phenoxys and to the characterization of many new radicals. The results from esr work will be introduced where pertinent, but a detailed discussion of the many spectra that have been published is considered beyond the scope of this review. Excellent summaries of the esr method (232,325) and its application to phenoxy radicals have appeared (44,205).The literature has been reviewed through September 1966; a number of later references are included. III. Generation of Phenoxy RadicalsA.