Using the multiple correlation method, the efficiency of operators'' work at heat power plants (HPP) was measured by a complex of psychophysiological parameters, recorded at the beginning and at the end of the work day. Important functions include the operative memory, the capacity to concentrate and to switch attention, the velocity of the visual-motor reaction, the amount of processed visual information and age. The efficiency estimate is most highly correlated (r = 0.71) with the complex of psychophysiological characteristics recorded at the end of the work day. Operative memory function is the most useful criterion of professional fitness of HPP operators (r = 0.65). Regression equations are proposed for prediction of professional fitness to the work of HPP operators based on a number of psychophysiological characteristics, which may be useful in hiring and training.