Abstract: The subject invention pertains to a spray nozzle apparatus and method of use. The subject spray nozzle can be used to spray atomized fluid. The atomized fluid can then be incident on a heated surface such that heat is transferred from the heated surface to the atomized fluid. The subject invention also relates to a spray-cooling system and method of use. The subject spray-cooling system can incorporate a spray nozzle and a heat transfer plate. A device to be cooled, such as a laser diode, microwave amplifier, or other high power electrical device, can be placed in direct thermal contact with the heat transfer plate. The spray from the spray nozzle can then be sprayed onto the heat transfer plate. In a specific embodiment, a cellular transfer plate can be used and the spray from the spray nozzle can be sprayed into a cellular cavity or compartment, within the heat transfer plate. Heat is transferred from the heat source to the sprayed liquid via the wall of the heat transfer plate.