In the title compound, C(14)H(16)N(2)O(2)S, the thia-zolidine ring is planar [maximum atomic deviation = 0.0080 (14) Å] and twisted slightly with respect to the phenyl ring, making a dihedral angle of 4.46 (14)°. The butyl group displays an extended conformation, with a torsion angle of 169.4 (4)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules, forming supra-molecular chains.