Laser ignition experiments were performed to determine the ignition time of nanoscale particle diameter composites of aluminum (Al) and molybdenum trioxide (MoO3). Ignition time and burn rate were measured as a function of stoichiometry and also as a function of Al particle diameter, which ranged from 17.4 nm to 20 mum. Composites were pressed into solid cylindrical pellets with a 4.5-mm diameter and length and with a constant 38% theoretical maximum density (TMD). A 50-W CO2 laser provided the ignition source and high-speed digital images were used to determine ignition time and burn rates. Results indicate that nanoscale Al particle composites show significantly reduced ignition times that varied from 12 ms up to 6 s for nanometer compared with micrometer scale Al particle composites, respectively. (C) 2004 The Combustion Institute. Published by Elsevier Inc. All rights reserved.