Ag(I)/ZSM-5 catalyst was prepared and characterized spectroscopically in relation to its photocatalytic reactivity for the photodecomposition of nitric oxide. UV irradiation of the Ag(I)/ZSM-5 catalyst in the presence of NO leads to efficient catalytic conversion of NO into N-2, O-2, and other nitrogen oxides. Emission and synchronous-scan photoluminescence spectra indicate the presence of several environments for the Ag(I) ions in the ZSM-5 host. Ground- and excited-state electronic structure calculations for models in which [Ag+](n) ions (n greater than or equal to 1) are coordinated to NO molecules, suggest that N-O bonds are stronger in the ground state while N-N and O-O bonds are stronger in certain excited states. The luminescence and molecular orbital data suggest that more than one catalytic site for the photodecomposition of NO is present in Ag(I)/ZSM-5. The results of EXAFS have been used in support of the excited-state assignments.