The author examines different models of interrelationships between the processes of energy release and absorption. He concludes that there is not yet enough information to accurately formulate the relationship between the temperature of the furnance in the reaction zone and various electrochemical and process indices. It is possible only to advance several hypotheses requiring further verification. If they are proven, however, it would then be possible to use the melt discharge temperature to control the furnace operating regime. For a phosphorus furnace, it can be reliably stated that there is a connection between the temperature and the acidity coefficient M//a. Any deviations from this relationship should be regarded as deviations from the normal furnace operating regime.