Nanosized MgO is a functional material showing a great promise as destructive adsorbent for toxic chemical agents, unique optical electronic, magnetic, thermal, and mechanical properties, as well as in good bactericidal performance in aqueous environments and in the cancer therapy. In this study, MgO nanoparticles are obtained by thermal decomposition of nanosized Mg(OH)(2), which are synthesized by means of an innovative, time and cost-effective, scalable, and patented method. The nanoparticles are characterized by means of several techniques such as thermal analyses, X-ray diffraction analysis, infrared spectroscopy, transmission electron microscopy, atomic force microscopy, and surface area measurements (BET). After a pseudomorphic decomposition of the hydroxide precursor, pure and crystalline MgO nanoparticles are obtained. These nanoparticles are roughly spherical, monodispersed, and monocrystalline, having size <= 10 nm. Moreover, they exhibited a surface area up to 178 m(2)/g, revealing a bimodal mesoporous distribution with the important part of the pores with dimensions peaked at 4.87 nm.