We fabricated Co-coated SiOx nanowires and investigated the effects of thermal annealing on their properties. The sputtering process resulted in the formation of a relatively smooth Co shell layer, whereas subsequent thermal annealing generated the Co3O4 phase. The photoluminescence (PL) spectrum was not changed by the Co-coating, whereas the thermal annealing induced new peaks in the yellow and ultraviolet regions. Possible emission mechanisms were discussed. Based on the magnetization measurements of the SiOx-core/Co-shell nanowires, we obtained small and negligible hysteresis loops for the as-fabricated and thermal annealed samples, respectively. (C) 2009 Elsevier B.V. All rights reserved.