A novel Ni(II) coordination polymer with flexible 4,4′-oxybis(benzoic acid) (oba) and rigid 4,4′-bipyridine was prepared hydrothermally and crystallographically characterized. It shows an unusual μ-oxo(O 2− ) bridged dinickel(II) polymer. In the dimetal core, each metal center is six-coordinated to three carboxylate oxygen atoms from two different oba ligands, two nitrogen atoms of distinct 4,4′-bipyridine and one bridging oxygen forming a distorted octahedron.Upon complexation, nickel complex exhibits intense purple fluorescence (413.8nm) which may originates to the O 2− Ni 2+ (LMCT) in addition to the peaks of intraligand π–π ∗ transition of oba ligand (317.7 and 720.7nm). Moreover, nickel crystals possess preferable photocatalytic decomposition of RhB solution.