We synthesized crystalline MgO nanowires on Au-coated substrates by the heating of MgB2 powders. We carried out the thermal annealing on Au-coated substrates prior to the MgO deposition process.. affecting the morphology of the final MgO structures. The produced nanowires were of cubic MgO structures with diameters in the range of 40-200 nm. We discussed the possible growth mechanism. Photoluminescence spectrum of the MgO nanowires under excitation at 325 nm showed a visible light emission. (c) 2006 Elsevier B.V. All rights reserved.