Four lanthanide coordination polymers formulated as {[La₃L₉(H₂O)₃]EtOH · H₂O}_n 1, {[Pr₂L₆(H₂O)₂]HL · H₂O}_n 2, {[Dy₂L₆(H₂O)]0.5HL · H₂O}_n 3 and {[Ho₂L₆(H₂O)]0.5HL · H₂O}_n 4 and HL = trans-2-butenoic acid have been synthesized from the corresponding pure lanthanide oxide and HL acid in water at pH 3. The compounds were characterized by chemical analysis, IR spectroscopy, thermogravimetry, variable-temperature magnetic susceptibility and single crystal X-ray diffraction studies. A common feature in these materials is the presence of two differentiated lanthanide nodes linked by carboxylates into extended chains. These are further connected by inter- and intra-molecular hydrogen-bonds involving ligand and solvate molecules. Weak ferromagnetic interactions appear to be operative in the Dy material.