MgO nanoparticles with an average size of 30 nm were prepared by a traditional sol-gel method using magnesium chloride and NaOH aqueous solution as the raw materials. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the products. The catalytic effect of the MgO prepared on the decomposition of ammonium perchlorate (AP) was investigated by differential thermal analysis (DTA). The results indicate that MgO nanoparticles have a good dispersibility and a uniform crystallite size, also have an intense catalytic effect on the decomposition of AP comparing with commercial product. (c) 2006 Elsevier B.V. All rights reserved.