The flow field between two horizontal surfaces arising from jet issuing from the lower surface and impinging normally on the upper surface have been experimentally investigated for a single jet and double jet. The velocity and pressure distributions in the impingement region were obtained over a Reynolds number range of 300-10 000 and a nozzle-to-plate spacing range of 0.5-4. The effects of Reynolds number and nozzle-to-plate spacing on the flow structure are reported. It is concluded that a subatmospheric region occurs on the impingement plate at nozzle-to-plate spacings up to two for Reynolds numbers greater than 2700 and that there exists a linkage between the subatmospheric region and the peaks in heat transfer coefficients. (C) 1999 Elsevier Science Inc. All rights reserved.