Two dinuclear trivalent cobalt complexes viz. [Co 2(P1-O)(AcO) (H 2O)(OH)](ClO 4) 3, (1) and [Co 2(P1-O)(AcO)(DPP)](ClO 4) 3, (2), where P1-O=N, N′, N″, N‴-tetrakis(2- methylpyridyl)-2-hydroxy-1,3-diaminopropane, AcO = acetate and DPP = diphenyl phosphate, containing three intervening bridges between the two cobalt(III) centers have been synthesized and characterized. Complex 1 was formed by the reaction of a divalent dicobalt complex [Co 2(P1-O)(AcO)](ClO 4) 2 with hydrogen peroxide. The X-ray crystallographic analysis shows that 1 contains a μ-acetato-μ-aqua-hydroxo-μ-alkoxo- dicobalt(III) core comprised of two distorted octahedral Co sites. Complex 2 also has two six-coordinated cobalt(III) ions with N 3O 3 set of donor atoms derived from the binucleating ligand, P1-OH and the oxygen atoms of acetate (OAc) and diphenyl phosphate (DPP) groups, rendering octahedral geometry around each cobalt(III). The distance between the two cobalt(III) sites in the complexes 1 and 2 is 3.38 and 3.35 Å, respectively that are close to the M...M distance in dinuclear metalloenzymes. Complexes 1 and 2 are also characterized by conventional spectroscopic methods such as UV-Vis, FT-IR, 1H, 13C and 31P NMR and ESI-MS spectroscopic methods. © 2012 Elsevier B.V. All rights reserved.