A novel cyclic tetranuclear cluster, [Co(H 2 O) 6 ][Co 4 (ccdp) 2 (H 2 O) 4 ]·8H 2 O·2CH 3 CN (1) with cobalt(II) ions sitting in a quadrilateral has been synthesized and fully characterized by exploiting the flexibility, chelating ability and bridging potential of a carboxylate rich dinucleating ligand, H 5 ccdp [H 5 ccdp=N,N ′ -Bis[2-carboxybenzomethyl]-N,N ′ -Bis[carboxymethyl]-1,3-diaminopropan-2-ol]. The crystal structure of 1 contains a [Co 4 II (H 2 O) 4 )] 2– core unit which is held together by two bridging benzoate potions of the ligands, ccdp 5– . Furthermore, the [Co 4 II (H 2 O) 4 )] 2– core unit is stabilized and charge neutralized by intermolecular hydrogen bonding and [Co(H 2 O) 6 ] 2+ , respectively.