In the mol-ecular structure of the title hydrazide derivative, C(27)H(24)ClN(3)OS, the acetohydrazide group is approximately planar, with a maximum deviation of 0.017 (3) Å. The dihedral angle between the naphthyl-ene system and the phenyl ring is 78.91 (18)°. The crystal structure is stabilized by one weak inter-molecular C-H⋯O hydrogen bond and two aliphatic C-H⋯π hydrogen-bonding associations.