The reactions of 1,4-dinitropyrazole with primary amines, hydrazines, hydroxylamine and amidines were studied. 1,4-Dinitropyrazole in these reactions served as the synthetic equivalent of nitromalonaldehyde. The reaction of dinitropyrazole with primary arylhydrazines proved to be a convenient approach to the synthesis of 1-aryl-4-nitropyrazoles.