The ignition temperature of the Al-CuO thermite was measured using DTA at a scan rate of 50 degrees C min(-1) in a nitrogen atmosphere. Thermite reactions are difficult to start as they require very high temperatures for ignition, e.g. for Al-CuO thermite comprising micron particles it is ca. 940 degrees C. It was found that the ignition temperature is significantly reduced when the binary Si-Bi2O3 system is added as sensitizer. Further improvement is achieved when the reagents are nano-sized powders. For the composition Al + CuO + Si + Bi2O3 (65.3:14.7:16:4 wt.%), with all components nano-sized, the observed ignition temperature is ca. 613 degrees C and a thermal runaway reaction is observed in the DTA. (C) 2010 Elsevier B.V. All rights reserved.