AbstractIn this paper the catalytic oxidation of a number of naphthols is described, copper‐collidine and copper‐pyridine complexes being used as catalysts.Generally speaking two types of reactions must be considered. The first type involves a direct oxidation of the naphthol by the cupric complex to free radicals which dimerize and give rise to dinaphthols. Some of these are oxidized further to naphthalene analogues of diphenoquinone (dinaphthones and bisnaphthalene indigo's). All these reactions may be accomplished by the cupric complex itself, and the function of oxygen is simply to regenerate the cupric‐ from the cuprous state.In the second type of reactions, which involve the formation of 1,4‐naphthaquinone derivatives, oxygen (or hydrogen peroxide formed from it) probably plays a more specific rôle. Hydrogen peroxide may also be responsible for some unidentified products formed from the dinaphthol derivatives.The naphthols investigated were: naphthol‐1, naphthol‐2, 2‐ethyl‐1‐naphthol, 4‐methyl‐1‐naphthol, 2‐ and 4‐chloro‐1‐naphthol. The products are listed in table 1. The redox potentials of 4‐(2′‐hydroxy‐1′‐naphthyl)‐1,2‐naphthaquinone and of diethyldinaphthone have been measured.The spectra of bis‐methylnaphthalene‐indigo and of natural indigo appear to be strikingly similar.The following new compounds are described: 4‐(di‐β‐naphthoxyl)‐1,2‐naphthaquinone and its phenazine, bis‐4‐chloronaphthalene indigo, 2,2′‐dichlorodinaphthone, bis‐4‐methylnaphthalene indigo, a black compound (C30H18O4)X.