From measurements of phosphorescence and triplet-triplet absorption spectra due to the lowest excited triplet π π* states of the title compounds together with the absorption spectra of their anthryloxy radicals, it is concluded that photolysis of nitroanthracenes gives rise to the nitro→nitrite rearrangement for a higher excited triplet state of  nπ* character, followed by the cleavage of nitrites to anthryloxy radicals and nitrogen (II) oxide. Except for the formation of anthraquinone monoxime via 9-nitroanthracenes, the existence of a keto-enol equilibrium between anthrone and 9-anthronol, and the recombination of two 9-anthryloxy raicals yielding 10, 10’ -bianthrone, the photophysics and photochemistry of 9-nitroanthracene are essentially identical with those of 9-benzoyl-10-nitroanthracene and 9-cyano-10-nitroanthracene.