We fabricated MgO/Ag core-shell nanowires, where core nanowires were coated with a conformal layer of Ag via sputtering. By subsequent thermal annealing, we generated Ag nanoparticles. Photoluminescence (PL) studies revealed that Ag-shell coating decreased the intensity of blue emission, whereas that of UV emission remained almost invariant. The subsequent annealing has induced an additional green emission band. We discuss here the possible mechanism by which the PL properties have been tailored by Ag-layer coating and by forming nanoparticles. This approach can be applied to tailor and improve the optical properties of different composite nanostructures. (C) 2011 Elsevier B.V. All rights reserved.