In the title compound, C(3)H(5)N(2) (+)·C(7)H(4)NO(4) (-), the benzene ring forms a dihedral angle of 40.60 (5)° with the imidizolium ring. The nitro-benzoate anion is approximately planar: the benzene ring makes dihedral angles of 3.8 (3) and 3.2 (1)° with the nitro and carboxyl-ate groups, respectively. In the crystal structure, the cations and anions are linked by inter-molecular N-H⋯O hydrogen bonds, forming a zigzag chain along the b axis.