The polarographic reduction of 2,4,6-trinitro diphenylamine was found to give three waves of nearly equal height in all pH regions in buffered solutions and also in unbuffered methanol-water mixtures. The waves were shown to be diffusion-controlled and irreversible on the basis of the usual criteria. Controlled-potential electrolysis at the limiting region of the third wave gave napp = 18 and thus it was shown that napp = 6 for each of the waves. It was concluded that each of the nitrogroups in the compound is reduced to the corresponding amino group, the nitro groups ortho to the NH group in the parent compound being reduced first followed by the other. Cyclic voltammetric experiments in unbuffered solutions gave evidence for a new redox system which was attributed to amine-quinone diimine intermediate couple. It was inferred that each of the nitro groups in the compound is reduced to the amino function via this intermediate. © 1981.