In the cation of the title compound, C(18)H(20)ClN(4)O(3)S(+)·Cl(-), the tetra-hydro-pyridinium ring assumes a half-chair conformation. The dihedral angle between the pyrazole ring and the naphthalene ring system is 75.19 (6)°. In the crystal, ions are linked into a three-dimensional network by N-H⋯O, N-H⋯Cl and O-H⋯Cl hydrogen bonds and weak π-π stacking inter-actions with centroid-centroid distances of 3.608 (2) Å.