In the crystal structure of the title complex, [Tb(C(6)H(4)NO(2))(C(2)O(4))(H(2)O)(2)](n), the Tb(III) cation is coordinated by four O atoms from two oxalate ligands, two O atoms from two isonicotinate ligands and two O atoms from water mol-ecules within a distorted square-anti-prismatic coordination. The Tb(III) cation, the isonicotinate anion and the two crystallographically independent water mol-ecules occupy general positions, whereas one of the two crystallographically independent oxalate anions is located on a center of inversion, and the second oxalate anion is located on a twofold rotation axis. The Tb(III) cations are linked by the oxalate and isonicotinate anions into layers, which are connected via inter-molecular hydrogen-bonding and π-π stacking [with centroid-to-centroid distances of 3.509 (2) and 3.343 (3) Å] inter-actions into a three-dimensional network.