The heat-flow rate and temperature of the heater are measured at various liquid subcooling boiling points. An experimental plant and the obtained results on the heat energy motion in the superficially boiling binary liquid mixtures are described. The experiments have used a quasi-stationary heating method which allows accurate specifying of the critical heat flux ( qkr ) and the temperature of the heater ( Th ). An experimental study of the superficial boiling has determined that the critical heat flux density depends significantly on the liquid subcooling. At the liquid nucleus temperature TL =300С in the mixture of water- n -butanol, 10% critical heat flux reaches a considerable size of 20.68 MW/m2, and at TL =300С - much less qkr =2.98 MW/m2. This is due to the increase in the temperature drop (∆ Т = Th kr + TL ) at the moment of qkr .