A microjet impingement cooling device for high power electronics was constructed from silicon wafers using microelectromechnical systems fabrication techniques. The array of 221, 0.277-mm-diam jets was tested using air as the coolant for jet diameter Reynolds numbers from 4.65 x 10(2) to 1.405 x 10(3). Heat transfer and pressure drop data were obtained for a range of mass rates extending up to the point of choked How and also for variable heat fluxes. The results were compared to an existing Nusselt correlation for jet impingement arrays that was found to significantly under-predict the heat transfer. A new correlation is provided that also accounts for variable air properties.