In this study, the explosion characteristics of coal powder in O-2-CO2 atmospheres are studied. All experiments are performed in a 20 L spherical vessel. The maximum explosion pressure and the maximum rate of pressure rise are derived from the pressure time evolutions. A three-zone theoretical model has been applied to calculate the flame speed. To overcome the drawbacks of the non-spherical flames generated by pyrotechnical igniters, a continuous ignition spark is used as an alternative ignition source. The experimental results show that maximum explosion pressures are similar when different ignition sources are used. The maximum rate of pressure rise and the flame velocity are very sensitive to the ignition source. (C) 2016 Published by Elsevier Ltd.