Two six-electron diffusion-controlled irreversible waves are obtained for the polarographic reduction of 2,4-dinitrodiphenylamine (DPA) in buffered and unbuffered media in all compositions of methanol-water mixtures. Based on the polarographic and coulometric data, it is suggested that each of the nitro groups is reduced to the corresponding amine in a single step via the diimine intermediate to give 2,4-diamino DPA as the final product. The influence of various factors such as structure of the depolariser, pH and composition of methanol on the reduction of the compound is also discussed. © 1980 Indian Academy of Sciences.