Graphical Abstract: Thiolato-bridged complex [CuI4CuII4(peampt)4Cl8]·2H2O (Hpeampt = 1-(2-pyridylethyl)amino) methylpropane-2-thiol) has been synthesized and characterized by the elemental analysis, IR and UV-vis spectroscopies and magnetic susceptibility measurement. The X-ray crystal structure analysis of this complex shows a localized mixed-valence octanuclear cage structure made up of four trigonal-bipyramidal CuIIN2SCl2, two trigonal CuIS2Cl, and two tetrahedral CuIS2Cl2 coordination sites. Temperature dependence of magnetic susceptibility (4.5— 300 K) shows that a fairly strong antiferromagnetic interaction is operating between the four CuII ions.