In this study, the decomposing deflagration properties of acetylene under temperatures down to -60 degrees C and pressures up to 0.2 MPa in a 1-L cylindrical closed vessel were experimentally investigated. The gases were ignited by an electric spark at the center of the vessel. The lower-limit pressures of decomposing deflagration by electric spark ignition were determined. The lower-limit pressure at 10 degrees C was 0.15MPa, and it gradually increased with decreasing temperature. The lower-limit pressure at -60 degrees C was 0.18MPa. The flame propagation properties, such as the pressure, were measured with pressure transducers mounted along the vessel. The maximum decomposing deflagration pressures and pressure rising rates also increased with decreasing temperature. (C) 2007 Elsevier Ltd. All rights reserved.