II-VI semiconductors are of interest due to their potential application as photovoltaic devices like hybrid solar cells. The efficiency of these devices may be improved mainly increasing charge carriers densities and interfacial processes. In order to reach this last purpose nanocrystalline materials are the best option as solar cells constituents. In this work we present a structural characterization of nanocrystalline ZnSe and ZnTe semiconductors obtained by mechanical milling. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and positron annihilation lifetime (PALS) measurements. PALS results were compared with ab-initio simulations using the MIKA program. The two-component density functional theory framework (TC-DFT) with the generalized gradient approximation (GGA) and the local density approximation (LDA.) was applied. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.