In the title compound, C(14)H(10)FN(3)O, the six- and five-membered rings of the isatin moiety and the six-membered ring of phenyl-hydrazone are nearly planar with r.m.s. deviations of 0.0003, 0.0004 and 0.007 Å, respectively. The dihedral angle between the phenyl ring and the isatin ring system is 6.09 (9)°. The mol-ecular structure is stabilized by a strong intra-molecular N-H⋯O hydrogen bond, leading to the formation of a pseudo-six-membered ring, generating an S(6) ring. The crystal structure features inter-molecular N-H⋯O inter-actions.