With electronic packages becoming more dense and powerful, traditional methods of thermal energy removal are reaching their limits. One method of direct contact cooling capable of removing high heat fluxes while still being compact in size is spray impingement cooling, but its heat transfer behavior is not understood well enough to enable systematic, practical system design. This work presents the results of a large parametric study of spray cooling using a number of different nozzle patterns. It was found that nozzles that use the fluid most efficiently to remove thermal energy were limited by low peak heat fluxes and that the highest peak heat fluxes were obtained when phase change was avoided. Multiple nozzle arrays allowed for higher peak heat fluxes but used fluid inefficiently due to interactions between neighboring sprays. In general, the geometric pattern of the nozzle arrays had little effect on overall heat transfer performance. (c) 2005 Published by Elsevier Ltd.