A study was conducted of heat transfer and hydrodynamic behavior for subcooled flow boiling of Freon-113, one of a group of fluorocarbons suitable for use in cooling of high-power-density electronic components. Problems arising from the excellent wetting characteristics and large solubility constants of fluorocarbons were also examined. The primary configuration was vertical upflow through a 0.500-in. ID stainless steel tube with direct resistance heating of the tube wall. Operating parameter ranges included up to 4.28 ft/sec velocity, 22.3 psia pressure, 61*F subcooling, 0.40 void fraction, 1.08 X 10-3 moles/mole dissolved gas, and 105 Btu/hr ft2 heat flux. Single-phase heat transfer was adequately correlated by standard methods. Boiling curves had a unique form dominated by large, discontinuous jumps in wall temperature at the incipient point on increasing heat flux traverses. Effects of velocity and subcooling on two-phase heat transfer followed conventional trends. Techniques were devised for accurate determination of the temperature dependence of the air-Freon-113 solubility constant and for measurement and control of dissolved gas content in the main loop. Dissolved gas effects were found to increase heat transfer significantly in the partial boiling mode. Data in the fully-developed boiling mode were successfully described by modifications of existing correlations. A conventional correlation provided, at best, an upper bound for the critical heat flux data. Models and analyses were formulated for predicting delayed nucleation and dissolved gas effects on incipience. Delayed nucleation and hysteresis were successfully eliminated by means of a special surface coating. Transition in gassy boiling heat transfer from gas-dominated to vapor-dominated modes was postulated with reference to adjusted saturation temperatures.