The title compound, C18H20F2N2O2S, was synthesized, and the structure was investigated by X-ray crystallography. The compound crystallizes in the monoclinic space group P2(1)/n with cell parameters a = 9.905(6) angstrom, b = 16.907(15) angstrom, c = 10.778(9) angstrom, beta = 98.831(5)degrees for Z = 4. The structure has been solved by direct methods and refined to R-1 = 0.0408 for 2905 observed reflections with I > 2 sigma(I). The piperazine ring is in a chair conformation. The geometry around the S atom is a distorted tetrahedron. The structure exhibits a weak intermolecular hydrogen bond of the type C-H... F.