The vapor-phase photodegradation of methanol to carbon dioxide was carried out over uranyl-anchored nanoporous MCM-41 and MCM-48 hosts (designated as UO 2 2++/MCM-41 and UO 2 2+/MCM-48, respectively) under simulated light and ambient conditions. Preliminary results indicate that the photoactivity of the latter is considerably decreased as compared to the former due to the presence of a smaller fraction of photoactive uranyl (UO 2 2+) ions in UO 2 2+/MCM-48. Copyright © 2006 American Scientific Publishers All rights reserved.