Formation of ceria nanoparticles in 2% divinyl benzene (dvb) crosslinked 4-vinyl pyridine (4vp) polymer [poly(4vp-co-dvb)] microspheres was investigated. The polymer was prepared by free radical Suspension polymerization method. Poly(4vp-co-dvb)/ceria nanocomposites were prepared by reacting CeCl(3)(.)7H(2)O and NaOH in the presence of poly(4vp-co-dvb) at room temperature in aqueous media. The mole ratio of the metal to polymer was varied from 2.5 to 10% with an increment of 2.5. The polymer and nanocomposities were characterized by various spectrochemical methods. The coordination of nitrogen atoms of the polymer with Ce(IV) of ceria (CeO2) has been confirmed from X-ray photoelectron spectroscopy (XPS). The method has yielded ceria nanoparticles in an average size of 15 nm according to transmission electron microscopy. Differential scanning calorimetry, thermogravimetric analysis, X-ray diffractometry and XPS analysis with respect to mole percentage of ceria in the composite are discussed. (c) 2006 Wiley Periodicals, Inc.