Poly[[triaqua-(μ(3)-4-oxidopyridine-2,6-dicarboxyl-ato)holmium(III)] mono-hydrate].

In the title coordination polymer, {[Ho(C(7)H(2)NO(5))(H(2)O)(3)]·H(2)O}(n), the Ho(III) atom is eight-coordinated by a tridentate 4-oxidopyridine-2,6-dicarboxyl-ate trianion, two monodentate anions and three water mol-ecules, forming a distorted bicapped trigonal-prismatic HoNO(7) coordination geometry. The anions bridge adjacent Ho(III) ions into double chains. Adjacent chains are further connected into sheets. O-H⋯O hydrogen bonds involving both coordinated and uncoordinated water mol-ecules generate a three-dimensional supra-molecular framework.