Quantum size effect was demonstrated in ZnO/mesoporous silica nanocomposites prepared by two different routes: the reverse micelle strategy and the colloidal method owing to a fine tuning of particles grown by the control of mesopore size. N-2 adsorption-desorption measurements, Atomic Absorption and Photoluminescent spectroscopy have evidenced the efficient loading and growth of ZnO nanoparticles in the channels of the mesoporous silica matrix. The present work illustrated that both methods are quite efficient in the preparation of short wavelength (blue) laser nanocomposite. (c) 2007 Elsevier B.V. All rights reserved.