The Mo(VI) atom in the title co-crystal, [Mo(C(14)H(12)N(2)O(4))O(2)(H(2)O)]·0.5C(10)H(8)N(2), is O,N,O'-chelated by the deprotonated Schiff base and coordinated by the oxide and water O atoms in an octa-hedral geometry. The five-membered chelate ring is planar (r.m.s. deviation = 0.019 Å), but the six-membered chelate ring is puckered (r.m.s. deviation = 0.108 Å). Two mononuclear mol-ecules are linked across a center of inversion by an O-H(water)⋯O hydrogen bond; adjacent dinuclear units are linked by an water-4,4'-bipyridine O-H⋯N hydrogen bond, generating a linear chain structure. The 4,4'-bipyridine mol-ecule is disordered over two positions in a 1:1 ratio.