The title compound, C14H11FN2OS, contains two mol-ecules (A and B) in the asymmetric unit, with different conformations. In mol-ecule A, the dihedral angles between the central thio-urea grouping and the phenyl and fluoro-benzene rings are 28.77 (8) and 41.82 (8)°, respectively, and the dihedral angle between the ring planes is 70.02 (9)°. Equivalent data for mol-ecule B are 8.46 (8), 47.78 (8) and 52.99 (9)°, respectively. Both mol-ecules feature an intra-molecular N-H⋯O hydrogen bond, which closes an S(6) ring. In the crystal, A+B dimers linked by pairs of N-H⋯S hydrogen bonds generate R 2 (2)(8) loops.