The development of light and efficient Compact Heat Exchangers (CHE) for automotive or aerospace applications has motivated recent research for the energetic optimisation of these devices. Owing to their geometrical complexity, such a goal requires valuable knowledges on the more simple case of a single plate in a fluid flow. The purpose of this study is to present an experimental and numerical study of the heat transfer between an incompressible fluid and a blunt flat plate with constant wall temperature. An experimental test rig is built in which air flows around a constant temperature copper plate. The Reynolds number defined on the plate thickness is varied from 120 to 500. Flow measurements are achieved with laser anemometry and the temperature field is determined using the cold wire technique. For each experiment, the experimental data are compared to Direct Numerical Simulations. Classical features of the flow are observed, i.e. a recirculating vortex near the leading edge of the plate, which is followed by a boundary layer from which vortices are alternately shed from both faces of the plate. Unlike previous studies, a particular attention is paid to the longitudinal distribution of the heat transfer coefficient for low to moderate Reynolds numbers. It is shown that a Direct Numerical Simulation of the flow and heat transfer around a thick plate is an efficient tool of optimisation which could be used for the design of industrial CHE. (C) 2007 Elsevier Ltd. All rights reserved.