In the title coordination polymer, [Mn(C(8)H(5)NO(5))(H(2)O)(4)](n), the Mn(II) atom is coordinated by two carboxyl-ate O atoms from two 5-carboxyl-ato-1-carboxyl-atomethyl-2-oxidopyridinium (L(2-)) ligands and by four water mol-ecules in a distorted octa-hedral geometry. The L(2-) ligands bridge the Mn atoms into an infinite chain motif along [100]; the chains are further inter-linked by O-H⋯O hydrogen bonds into a three-dimensional supra-molecular net.