Well-crystallized MgO nanosheets have been prepared with MgB2 as a precursor without any catalyst via a simple chemical vapor deposition (CVD) method. The nanosheets are grown parallel to (2 0 0) plane according to the high-resolution transmission electron microscopy profiles. At the same time, MgO nanowires are formed in the different area of substrate, which is the result of the difference in local super-saturation. Consequently, we propose that the growth mechanism depends on the surface energy and the local super-saturation in the system. (C) 2010 Elsevier B.V. All rights reserved.