The mol-ecule of the title compound, C(11)H(11)N(3)O(5), exists as the E isomer as it is stabilized by an intra-molecular hydrogen bond. Except for the methyl H atoms, all atoms lie in special positions on a mirror plane and form a large conjugated system; the methyl H atoms are disordered about the mirror plane. In the crystalline state, bifurcated intra- and inter-molecular N-H⋯O hydrogen bonds and four inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into large perfectly planar sheets. Along the c axis, the N-N bond center approaches the phenyl-ring centroids of its neighbouring mol-ecules above and below to give π-π overlap (at a distance of ca 3.57 Å), thus fusing the mol-ecules into a three-dimensional framework.