A novel manganiferous coordination polymer, [Mn(II)-(HL)(2)](n) (H2L = 4-hydroxynicotinic acid) (1) was hydrothermally synthesized. Interestingly, an in situ ligand synthesis for HL from 3,4-pyridinedicarboxylic acid precursor was observed. Structure analysis indicates I is built up from building blocks of Mn(II)-centered octahedron and HL ligand. The mu(3)-HL ligand plays dual roles for the formation of 1-D framework: chelate and bridge.