A series of previously reported mononuclear Cu(II) and homodinuclear Cu(II)Cu(II) complexes, as well as, novel mononuclear Cu(II), homodinuclear Cu(II)Cu(II), and heterodinuclear Cu(II)Ni(II) complexes of a phenol-based dinucleating ligand with two different N(amine)(2)O-2 and N(imine)(2)O-2 coordination sites, were synthesized and characterized by elemental analyses, infrared and electronic absorption spectroscopies and conductivity measurements. The electrochemical behavior and catecholase-like activity of the complexes were also studied using cyclic voltammetry and UV-vis spectrophotometry, respectively. Our results show that the dinuclear complexes are more effective catalysts in the oxidation of catechol to the corresponding quinone than the mononuclear complexes. Furthermore, the homodinuclear Cu(II)Cu(II) complexes show greater catalytic activity compared to the corresponding heterodinuclear Cu(II)Ni(H) complexes. (c) 2005 Elsevier B.V All rights reserved.