In order to study the heat transfer characteristics of flow boiling under reduced gravity conditions, a series of experiments have been conducted on flow quenching of a hot flat surface by Freon-113 aboard the KC-135 parabolic aircraft. The instantaneous heat flux and temperature on the horizontal surface were measured using a heat flux microsensor comprising of two 2-mu m thick thermopiles and one resistance temperature sensor. During film boiling, heat transfer from the hot surface to the flowing liquid was found to be reduced under microgravity compared to normal gravity conditions due to the thickening of the Vapor layer. Also, the wall superheat and the surface hear flux at the onset of rewetting and the maximum heat flux during quenching of the hot surface were found to increase with the inlet liquid subcooling, mass flux and gravity level. The effect of microgravity was more important for low flow rate results and decreased al high flow rates.