In a template synthesis from copper(II) acetate, 2,6-diacetylpyridine, and semioxamazide (NH 2 CO CONHNH 2 ), two new copper(II) complexes, [Cu(dapsox)(H 2 O)] H 2 O and [Cu(Hdapsox)(H 2 O)]ClO 4 , (where H 2 dapsox = 2 ,2 -(2,6-pyridindiyldiethylidene)dioxamohydrazide) were obtained and characterized. The structure of the former complex was determined by a single-crystal X-ray analysis. Cu I I is located in a square pyramidal environment. The polydentate ligand, dapsox 2 - , is coordinated in dianionic form, as an unsymmetrical quadridentate planar system forming one six-membered and two five-membered metal-chelate rings. The fifth coordination site is occupied by a water molecule.