NiO nanoparticles with an average size of 10 nm were prepared by a solid-state reaction using nickel acetate and sodium hydroxide as the raw materials and the Tween 80 as dispersant. The reaction was studied by DTA, TG, XRD and FTIR. The size and morphology of NiO nanoparticles were characterized by TEM. The catalytic effect of the NiO nanoparticles for thermal decomposition of ammonium perchlorate (AP) was investigated by DTA and TG. The catalytic performance of NiO nanoparticles is superior to that of bulk NiO particles. Adding 2% of NiO nanoparticles to AP decreases the decomposition temperature by 93 C and increases the heat of decomposition from 590 to 1490 J g(-1). (C) 2005 Elsevier B.V. All rights reserved.