A new bimetallic cluster complex with the formula [{Co(phen) 2} 2V 4O 12]·H 2O was synthesized from the hydrothermal reaction of V 2O 5, H 2C 2O 4, Co(NO 3) 2, 1,10-phenanthroline (phen), (C 4H 9) 4NOH and water. The compound crystallizes in an orthorhombic system with space group Pbcn and unit cell parameters a=19.106(3) A ̊ , b=15.250(3) A ̊ , c=16.321(2) A ̊ , V=4755.4(13) A ̊ 3, Z=4 and R=0.0318. The bimetallic cluster complex [{Co(phen) 2} 2V 4O 12]·H 2O is composed of a discrete V 4O 12 4− cluster covalently attached to two [Co(phen) 2] 2+ fragments and the discrete hexanuclear bimetallic clusters of [{Co(phen) 2} 2V 4O 12]·H 2O are further extended into interesting three-dimensional supermolecular arrays via π–π stacking interactions of phen groups. Other characterizations by elemental analysis, IR, and thermal analysis are also described.