The cation and anion of the title mol-ecular salt, C(7)H(10)NO(+)·C(6)H(2)N(3)O(8) (-), are linked via an N-H⋯O hydrogen bond. An intra-molecular O-H⋯O hydrogen bond is also found in the anion. In the crystal, the anions self-assemble via O-H⋯O hydrogen bonds, forming a C(9) supra-molecular chain the b axis. Further inter-molecular N-H⋯O inter-actions also occur.