Energy expended in the tablet compression process was calculated by consideration of the magnitude and relation between the several compression variables. In the compression of about 0.4 Gm. of unlubricated sulfathiazole granulation to a maximum force of 1200 Kg, on the lower punch with flat-faced 3/8-inch punches, about 8.6 calories were expended. For about the same weight of lubricated granulation the corresponding value was about 2.0 calories. By considering that only energy expended in the process of eliminating void space to form the tablet caused a temperature rise in the tablet, the temperature rise expected in the lubricated or unlubricated tablets mentioned above would be about 5°. When the energies expended in the processes of tablet ejection, overcoming wall friction and removing the upper punch from the die, were summed for a single punch machine making these tablets at the rate of 100 per minute, it was found that 43 kilocalories would be expended in each hour of operation if the tablets were unlubricated. If lubricated granulation were used the value would be 3 kilocalories. The bulk of these expenditures would probably cause heating of the punches and die and if the granulation was either poorly lubricated or unlubricated the heating might be severe.