In the title compound, C 22 H 22 N 2 O 4 , the central pyrazoline ring exhibits a nearly planar structure (r.m.s. deviation = 0.025 Å) despite having two sp 3 carbon atoms. The pyrazoline ring subtends dihedral angles of 4.61 (1) and 87.31 (1)° with the pendant benzene ring and naphthalene ring system, respectively. The dihedral angle between the planes of the benzene ring and the naphthalene ring system is 89.76 (2)°. An intra-molecular O-H⋯N hydrogen bond forms an S (6) ring motif. In the crystal, inversion dimers formed by pairwise weak N-H⋯N hydrogen bonds generate R 2 2 (4) loops and the dimers are linked by pairwise C-H⋯O hydrogen bonds [which generate R 2 2 (8) loops] into [100] chains.