A com. epoxy resin was filled with white barite (65-80% by mass) and studied by differential scanning calorimetry, dynamic mech. thermal anal and thermogravimetty. Flammability of the composites was established by a horizontal burning method. Shore D hardness was also detd. Addn. of the finer resulted in a redn. of the exothermal effects during cross-linking and in improving thermal stability of the composites.