The imidazolate-bridged binuclear copper(II)-copper(II) complex [(dien)Cu(μ-im)Cu(dien)](ClO 4 ) 3 and related mononuclear complexes [Cu(dien)(H 2 O)](ClO 4 ) 2 , [Cu(dien)(Him)](ClO 4 ) 2 were synthesized with diethylenetriamine (dien) as capping ligand. The crystal structure of mononuclear [Cu(dien)(Him)](ClO 4 ) 2 and binuclear complex [(dien)Cu(μ-im)Cu(dien)](ClO 4 ) 3 have been determined by single crystal X-ray diffraction methods. The mononuclear complex [Cu(dien)(Him)](ClO 4 ) 2 crystallizes in the orthorhombic, Pca2 1 with a=9.3420(9)A, b=12.3750(9)A, c=14.0830(9)A, β=90.000(7) o and Z=4 and binuclear complex [(dien)Cu(μ-im)Cu(dien)](ClO 4 ) 3 crystallizes in the monoclinic space group P2 1 /a, with a=15.017(7)A, b=11.938(6)A, c=15.386(6)A, β=110.30(4) o and Z=4. The molecular structures show that copper(II) ions in an asymmetrically elongated octahedral coordination (type 4+1+1) and in binuclear complex Cu(1) atom has a asymmetrically elongated octahedral coordination (type 4+1+1) and Cu(2) atom exhibits a square base pyramidal coordination (type 4+1). The bridging ligand (imidazolate ion, im) lies nearly on a straight line between two Cu 2 + , which are separated by 5.812A, slightly shorter than the value in copper-copper superoxide dismutase (Cu 2 -Cu 2 SOD). Magnetic measurements and electron spin resonance (ESR) spectroscopy of the binuclear complex have shown an antiferromagnetic exchange interaction. From pH-dependent cyclic voltametry (CV) and electronic spectroscopic studies the complex has been found to be stable over a wide pH range (7.75-12.50).