The polymeric ligand (resin) was prepared from 2-hydroxy-4-methoxybenzophenone with Ethane Diol in the presence of polyphosphoric acid as a catalyst on constant heating at 160 degrees C constant heating for 13 h. The poly[(2-hydroxy-4-methoxybenzophenone) ethylene] (HMBP-ED) form 1:2 metal:ligand polychelates with La(III), Pr(111), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III). The polymeric ligand and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, IR-spectroscopy. NMR and thermogravimetric analyses. The molecular weight was determined using number average molecular weight ((M) over barn) by a vapour pressure osmometry (VPO) method. All the polychelates are paramagnetic in nature except La(III). Ion-exchange studies at different electrolyte concentrations, pH and rate have been carried out for lanthanides(III) metal ions. (c) 2007 Elsevier Ltd. All rights reserved.