The interaction of nitric oxide with Ce0.75Zr0.25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O-2 CO-reactant on the nature and relative surface abundance of the resultant mono- and dimeric NO species was elucidated. The thermal stability of the surface nitrosyl complexes and their reactivity toward dioxygen were also examined. (c) 2006 Elsevier B.V. All rights reserved.