The title compound, (C3H12N2)2[Ce(C7H3NO4)3](NO3)- 3.5H2O, is a nine-coordinate Ce complex obtained from a proton-transfer compound. The molecular structure contains three pyridine-2,6-dicarboxylate species as tridentate ligands and two propane-1,3-diaminium cations as counter-ions. The asymmetric unit also contains one nitrate anion and 3.5 uncoordinated water molecules. In the crystal structure, a wide range of hydrogen-bonding interactions connect the various fragments into a supramolecular structure.