In the polymeric title compound, [Ca(C(7)H(3)NO(4))(H(2)O)(C(2)H(6)OS)](n), the Ca(II) ion is coordinated in a distorted penta-gonal-bipyramidal CdNO(6) geometry. The crystal packing is stabilized by O-H⋯O hydrogen bonds and π-π stacking inter-actions between the aromatic rings of pyridine-2,5-dicarb-oxy-late with centroid-centroid distances of 3.6166 (13) Å.