The crystal structure of the title complex, [Yb(2)(C(8)H(4)O(4))(2)(C(2)O(4))(H(2)O)(2)](n), features an extended three-dimensional framework made up of Yb(3+) ions coordinated by terephthalate ligands, oxalate ligands and water mol-ecules. The Yb(3+) ion has a distorted square-anti-prismatic coordination formed by one aqua ligand, two O atoms from an oxalate ligand and five O atoms belonging to four terephthalate anions. Two symmetry-independent terephthalate anions, as well as the oxalate anion, occupy special positions on inversion centers. The water molecule participates in O-H⋯O hydrogen bonding with both terephthalate anions.