Employing the method of the joint combustion of organosilicon compounds with benzotrifluoride in oxygen, the formation enthalpies of 1,1-dimethyl-1-silacyclobutane, 1,1,3,3-tetramethyl-1,3-disilacyclobutane, and 1,1,3,3,5,5-hexamethyl-1,3,5-trisiliacyclohexane were determined for the first time.