A novel decanuclear Co(II) cluster, [Co(10)(Q)(12)(μ(6)-CO(3))(4)]·2.5DMF (1) (Q = 8-hydroxyquinoline), has been synthesized under solvothermal conditions and characterized by powder XRD, TGA and IR spectroscopy. Single-crystal X-ray diffraction analysis shows that 1 represents a new type of decanuclear cobalt cluster with an approximate supertruncated tetrahedral shape coordinated with coexisted Q ligands and in situ formed μ(6)-bridging CO(3)(2-) anions. Meanwhile, 1 is the largest aggregate in metal-Q coordination chemistry. Another distinguishing feature of 1 is the adamantane-like metallic skeleton with point symbol {6(3)}(2){6}(3), which is observed in the polynuclear metal complexes for the first time. Furthermore, it is considered that the in situ formed CO(3)(2-) anions have a crucial effect on the formation of the resultant unexpected polynuclear structures. The magnetic studies show that antiferromagnetic (AF) interactions exist within 1.