The polymeric ligand (resin) was prepared from 2-hydroxy-4-methoxybenzophenone with 1,3-propane diol in the presence of polyphosphoric acid as a catalyst on constant heating at 160 degrees C for 13 h. The poly[(2-liydroxy-4-metlioxybeiizopheiioiie) propylene] (HMBP-PD) form 1 : 2 metal/ligand polychelates (metal-polymer complexes) with La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), and Dy(III). The polymeric ligand and its polychelates (metal-polymer complexes) 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,,) by a vapor pressure osmometry (VPO) method. Activation energy (E) of the resin was calculated from differential scanning calorimetry (DSC). 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 Wiley Periodicals, Inc.