An isoperibol calorimeter is described. Its operation involves the drop of a sample from temperatures up to 1373 K into a metal block at 298.15 K. By this method the enthalpy contents of the samples can be measured. The calibration factor, obtained by electrical and drop calibrations, had a reproducibility of +/-0.11%. The calorimeter was tested by determining the enthalpy of silver; agreement with the data of Barin was within a range of +1%.