MgO nanopowders were synthesized directly in torch flame of an oxygen microwave plasma using Mg granules as a source material. The plasma torch vaporized Mg granules immediately and Mg vapors were explosively oxidized producing MgO powders. It was observed from the FETEM images that size of the MgO particles is approximately 10-50 nm, showing various particle shapes such as hexahedrons, plates, and rectangles. Also, the surface area and pore distribution properties of as-produced sample were analyzed by a nitrogen adsorption apparatus. This synthetic method may be suitable for a direct continuous preparation and mass production of MgO nanoparticles. (c) 2006 Published by Elsevier B.V.