In the title compound, C16H11F3N4OS, the dihedral angle between the aromatic ring systems is 69.15 (10)°. Intramolecular N—HN and N—HO hydrogen bonds generate S(5) and S(6) rings, respectively. A short N—HF contact also occurs. In the crystal, inversion dimers linked by pairs of N—HO hydrogen bonds generate R 2 2(8) loops. The dimers are linked by N—HF hydrogen bonds, forming polymeric chains propagating in . π–π interactions also exist between the centroids of the benzene rings of the 2-oxoindoline group at a distance of 3.543 (3) Å and a short C=Oπ contact occurs. Two F atoms of the trifluoromethyl group are disordered over two sets of sites in a 0.517 (8):0.483 (8) ratio.