A process for the preparation of diaminodinitropyridine or diaminodinitrobenzene by contacting an aminopyridine or aminobenzene with oleum and nitric acid, wherein the improvement comprises adding at least about 1% molar excess of nitric acid, based upon the aminopyridine or aminobenzene, with stirring for at least two hours to form first the intermediate sulfonic acid, and then diaminodinitropyridine or diaminodinitrobenzene, and use of such products in the preparation of rigid rod polymers is disclosed.