The title compound, C(14)H(12)N(4)O(3)S, is an inter-mediate of Dexlansoprazole, a proton pump inhibitor (PPI) mainly developed for anti-ulcer activity. The absolute configuration of the title compound was determined as R. The crystal structure reveals that the mol-ecules form chains along the b axis through N-H⋯N and C-H⋯O hydrogen-bonded dimers. These chains are connected via weak C-H⋯O hydrogen bonds.