The principle of the method specified is weighing a test portion into a glass coking bulb having a capillary opening and placing it in a metal furnace maintained at a temperature of approximately 550 °C, thus quickly heating the test portion to the point at which all volatile matter is evaporated out of the bulb, while the heavier residue remaining in the bulb undergoes cracking and coking reactions during a specified heating period, removing the bulb, cooling it in a desiccator and weighing again. The method may be used to determine amounts of carbon residues in the range of 0,01 % (m/m) to 30,0 % (m/m), left after evaporation and pyrolysis.