An experimental investigation on flow structure and heat transfer from a single round jet impinging perpendicularly on a flat plate has been performed. Heat transfer has been studied by means of thermography. The influence of nozzle-to-plate distance and Reynolds number oil local heat transfer coefficient has been investigated. Based on the experimental results of this investigation as well as on experimental data from the literature, correlations for heat transfer coefficients have been developed. Similar correlations are presented for heat transfer between a two-dimensional impinging jet and a flat plate, based on literature data. Flow structure in a free jet has also been examined. (c) 2007 Elsevier Ltd. All rights reserved.