Three mini-bomb calorimeters of different types have been built with the common characteristics: 5cm3 of bomb volume, 10mg of sample, ∼420JK−1 of energy equivalent. These calorimeters can be calibrated by the electric method with the standard deviation of the mean of 0.02%. The results of burning reference material — benzoic acid (BA39i) by using the calorimeters 2 and 3 are in agreement with the recommended value, however, that by using the calorimeter 1 is 0.24% larger. A check experiment shows that the stirring effect in this calorimeter is not enough during the heating period. The energies of combustion of C60 and C70 have been determined by using the calorimeter 2.