A novel chain complex containing chromium(III) and alkali metal, namely, [Cr(salen) (NCS) 2K·H 2O] [salen 2− = N, N′-ethyenebis(salicyldiminato)] was prepared and its crystal structure was determined by X-ray diffraction technique. Each chromium atom is six-coordinated with the tetradentate ligand salen 2− in the equatorial plane and two NCS ligands in the axial positions via the N atoms. The bond lengths of the Cr atom with the coordinating atoms are comparable with other Cr III Schiff base complexes. Each K atom is also six-coordinated with five oxygen atoms and a sulfur atom. The bond lengths of KO fall into the range of potassium complexes of cyclic polyethers. There are two kinds of bridging modes: water molecules link two K atoms and phenolato groups in the Schiff base ligand and NCS anions link Cr and K atoms, resulting in a chain running in the direction parallel to the a-axis.