The present work describes the preparation and characterization of nanosized metal oxide particles (Fe2O3, ZnO and PbO) inside the mesopore channels of MCM-41 and MCM-48 silicate molecular sieves. The encapsulation of the metal oxides was carried out at room temperature by the incipient wetness method. Diffuse reflectance ultraviolet-visible spectroscopic studies showed a significant shift in the absorption band for the entrapped metal oxides as compared to the corresponding bulk oxides. Thus, confirming the quantum confinement of the incorporated nanoparticles in MCM-41 and MCM-48.