Mesoporous MgO particles have been synthesized through a novel template-free hydrothermal co-precipitation method using a Mg(NO3)(2) solution as the magnesium source and NaCO3 as precipitant. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and N-2 adsorption-desorption analysis. The results indicate that the MgO samples have a disordered mesoporous structure, a large BET surface area, and a large pore volume. The effect of reaction temperature on the MgO product BET surface area was studied. A possible formation and crystal growth mechanism for mesoporous MgO is proposed. (C) 2013 Elsevier Ltd. All rights reserved.