A novel three-dimensional copper molybdate with mixed ligands, [{Cu-II(2,2'-bpy)}{Cu-II(IN)(2)}{Mo4O12(OH)(2)}] (IN- = isonicotinate ion, 2,2'-bpy = 2,2'-bipyridine), 1, has been hydrothermally synthesized and structurally characterized, and this compound is built from an unprecedented tetranuclear molybdenum oxide cluster covalently bonded to two types of copper complex fragments, {Cu-II(2,2'-bpy)}(2+) and {Cu-II(IN)(2)}, via terminal oxygen atoms of {MoO6} octahedra. Crystal data for compound 1: monoclinic, space group C2/c, a = 16.4755 Angstrom, b 10.3714 Angstrom, c = 17.4382 Angstrom, alpha = 90.0000degrees, beta = 94.80980, gamma = 90.00000; V = 2969.24 Angstrom(3); Z = 2. Variable temperature magnetic susceptibility indicates that both ferromagnetic and antiferromagnetic interactions exist in 1.