Three unreported isomorphous Ln-containing metal–organic coordination polymeric complexes {LnL(HL)⋅(H 2 O) 2 } n (Ln=Sm (1), Eu (2) and Tb (3), CCDC 971815–971817) were synthesized based on 5-(2-hydroxyethoxy) isophthalic acid (H 2 L) under hydrothermal conditions. The obtained coordination polymers were characterized by IR, elemental analysis, thermal analysis and X-ray diffraction In solid state, these polymers featured 3-D supramolecular structures constructed by 2-D sheets through H-bonds. Investigation of photoluminescence properties of H 2 L and 1–3 showed all of them exhibited intense fluorescent emissions in the solid state at room temperature.