The asymmetric unit of the title salt C9H8N+·C12H9N4O7−, which exhibits anticonvulsant and hypnotic activities, comprises one anion and one cation interacting via an N—H...O hydrogen bond. In the anion, the six-membered rings are inclined each to other at 42.78 (9)°. The nitro groups in the 2,4-dinitrophenyl fragment attached to the aromatic ring in the para and ortho positions are twisted from its plane by 3.1 (2) and 45.5 (2)°, respectively. In the crystal, weak C—H...O hydrogen bonds consolidate the crystal packing. The Hirshfeld surface analysis revealed that O...H/H...O intermolecular contacts predominate in the crystal packing.