The reaction of lanthanum nitrate and 4-ethyl-benzoic acid (EBAH) in aqueous solution yielded the title polymer, [La(C(9)H(9)O(2))(3)(C(9)H(10)O(2))(H(2)O)](n). The asymmetric unit contains one La(III) atom, three 4-ethyl-benzoate (EBA) ligands, one neutral EBAH ligand and one coordinated water mol-ecule. Each La(III) ion is eight-coordinated by six O atoms from six bridging-bidentate EBA ligands, one O atom from a monodentate EBAH ligand and one water O atom in a distorted bicapped trigonal-prismatic geometry. The adjacent La(III) ions are linked by the carboxyl-ate groups of EBA ligands in a bridging-bidetate coordination mode, resulting in an infinite chain structure along the c axis. O-H⋯O hydrogen-bonding inter-actions involving the water mol-ecules, carboxyl-ate groups and carboxyl H atoms are formed within the one-dimensional polymer. One of the ethyl groups is disordered over two positions with occupancies of 0.717 (7) and 0.283 (7).