Periclase MgO having a nanosheet structure. The distance of the lattice planes in HRTEM is -0.24 nm-0.25 nm. Method of preparing periclase MgO having a nanosheet structure including preparation of Mg(OCH.sub.3).sub.2 in methanol solution. 4-methoxy benzy alcohol (MBZ) or 4-nitro benzyl alcohol (NBZ) or a mixture thereof is added in a ration of Mg to MBZ and/or NBZ of at least 1. Water/methanol mixture is added to the system. Solvent removal and calcinations in air is performed of the mixture.