The photocatalytic reduction of NO into N(2) in the absence and presence of hydrocarbons were investigated on MCM-41 mesoporous molecular sieves including Ti, V, and Mo ions. Special attention was paid to the origin of the differences in their photocatalytic reactivities. Ti-MCM-41 showed much higher photocatalytic reactivity for the direct decomposition of NO into N(2) and O(2) than V- and Mo-MCM-41. However, the reactions on V- and Mo-MCM-41 were remarkably enhanced in the co-existence of propane. Such enhancement was not observed on Ti-MCM-41, showing a sharp difference. It was found that the charge transfer excited states of V- and Mo-oxide species exhibit a high reactivity for the hydrogen abstraction from propane, leading to a high efficiency in the photocatalytic reaction of NO and propane on V- and Mo-MCM-41. However, Ti-MCM-41 did not exhibit high reactivity for the hydrogen abstraction.