The electric discharging tests under various conditions have been examined on those coal carbon electrodes which were heat-treated at temperatures between 800°C and 2800°C. The electrode specimens were prepared from Akabira weakly-caking coal (d.a.f.C=83.40%) and from Itmann strongly-coking coal (d.a.f.C=90.2%) by means of the cold binderless molding at pressures of 1000 and 2000kg/cm2 respectively.The change in the threshold voltage before and after repeating the short-duration discharge (ΔVr) was found to be sensitive to temperature and retention time of the heat treatment.The voltage change caused by a continuous discharge for five minutes (ΔVc) and thedimension of craters as well as the amount of consumption (Nc) exibited minima at about2000°C when they were plotted against heat treatment temperature (HTT). The voltagechange due to impulsive discharge (ΔVi) as well as the occurence of short-circuit (Ni) showed a maximum and a minimum for HTT. It was concluded that the coal carbon heattreated at about 2000°C was the most able one in all kinds of the discharging test examined.For Akabira-coal carbons, moreover, some correlations between ΔVr and HB/ρ (Brinnel hardness/electrical resistance), between ΔVi and σ/E (flexural strength/Young's modulus), and between ΔVc or Ni and contact potential have been found. It seems that the larger the mechanical strength, the flexibility and the electrical conductivity of carbon electrodes are, the better the electric discharging properties