Investigations of the mesoporous Mo-MCM-41 molecular sieves have shown that they include the tetrahedrally coordinated Mo-oxide species, which exhibits a photoluminescence spectrum attributed to the radiative decay from the charge transfer excited state. Also, the photocatalytic reaction of NO into N-2 was found to proceed much more efficiently in the presence of propane than in the absence of propane. The dynamic quenching of the photoluminescence spectrum by the addition of NO or propane indicates that the excited state of the highly dispersed Mo-oxide species having a tetrahedral coordination plays a significant role in this reaction.