A new lanthanide citrate motif of general formula [Ln(Hcit)(H₂O)₂·H₂O]_n, where Ln = Gd(1) and Nd(2) and Hcit^3- = C(OH)(COO^-)(CH₂COO^-)₂, has been synthesized hydrothermally from Ln₂O₃ and citric acid at 100 °C and characterized by elemental analysis, IR, TG-DTA, single-crystal X-ray diffraction, and magnetic measurements. The structures can be seen as .ladder chains. along the a axis, with dinuclear Ln₂O₂ units serving as “steps” and R-COO groups as “uprights”, which are connected by H bonds. The magnetic susceptibility between 2 and 300 K and the magnetization at 2 K, as a function of magnetic field between 0 and 5 T, were measured for both compounds. By modeling the magnetic behavior of the Gd compound with a dinuclear Hamiltonian H_S = gμ_B(S_A+S_B)B_o - J_oS_AS_B (S_A = S_B = 7/2), a ferromagnetic exchange interaction J_o = 0.039 cm^-1 was evaluated between Gd ions situated at d_o = 4.321 Å in dinuclear units bridged by two symmetry-related tridentate carboxylate oxygens. The EPR spectrum of the Gd compound is discussed. The temperature dependence of the susceptibility of the Nd compound is caused by the depopulation of the excited crystal-field levels when the temperature decreases. The magnetic-field dependence of the magnetization of 2 is attributed to the ground-state Kramers' doublet populated at 2 K. The g factor of this ground-state doublet is calculated from the data and compared with values for other compounds reported in the literature.