Heat Transfer experiments in spray cooling have been conducted in transient mode in the range of mass velocity of water of 10.233 ~ 20.167 Kg/(m2.s) and surface temperatures up to 950 °C. A copper specimen of dimensions 140 × 140 × 30 mm was used as a heat transfer surface with a mean roughness of the upper surface of 0.05 ~ 1.4 ºm. The temperature-time curve of two positions inside the metal were recorded, the first at 3 mm from the upper surface and the second at 15 mm of center line. A full cone nozzle was set up vertically at various displacements above surface. The spray pressure was controlled by an automatic hydraulic controller and the spray characteristics such as water mass velocity, water pressure and temperature were measured. An Iteration method is presented to solve the one-dimensional inverse heat conduction model. The evaporation heat transfer coefficient was assumed constant with time interval of 0.11111 s and the temperature distribution within the specimen were calculated. The estimated and measured value of temperatures at 3 mm from the surface are compared. The value of heat transfer coefficient was adjusted to give 0.004 °C difference between the measured and calculated values. The effect of water mass velocity and surface roughness on evaporation heat flux were investigated. The mass velocity of water is the most dominant parameter. The surface roughness is less important particularly at high surface superheating.