The interaction of 20 wt% 12-tungstophosphoric acid with CexZr1-xO2 solid solutions has been studied by PXRD, FTIR, IFT-Raman, H-2-TPR, NH3-TPD, diffuse reflectance UV-vis-NIR, and P-31 MAS NMR techniques. The study indicates that the Keggin anions are attached to Lewis metal ion centres and anion vacancies on CexZr1-xO2 supports through W=O terminal bonds. The Keggin units at the interface are chemically perturbed as indicated by non-intrinsic IR bands observed at 958 cm(-1) (W=O-ter bond), and 1052, 1102 cm(-1) (P-O bond). NH3-TPD shows that the Keggin anions fixed to Lewis sites and/or oxygen ion vacancies decrease the ammonia uptake on CexZr1-xO2 solid solutions. H-2-TPR shows modified redox behaviour of CexZr1-xO2 solid solutions due to the simultaneous reduction of ceria, decomposition of Keggin anions and the reduction of WO3. The broadening of P-31 MAS NMR and DR-UV-vis-NIR spectra demonstrate the existence of chemical interactions between the Keggin anions and Ce-x Zr1-xO2 supports. (c) 2008 Elsevier Inc. All rights reserved.