Combined PIV and numerical simulation, the flow characteristics of a single jet impinging on a protrusioned surface were investigated. And the heat transfer characteristics were explored on the basis of the numerical results. The flow structures of the single jet impinging on protrusioned surface in different cases are similar. The jet flow impinges perpendicularly onto the protrusion and then turns its flow direction. Mini flow separation occurs when the flow passes the edge of the protrusion and secondary impinging jet forms at the same time. The wall jet continues to develop along the radial direction after apart from the edge of the protrusion. Comparison with the case of smooth target surface shows that local Nusselt number increase occurs in the presence of protrusion. The local Nusselt number increases as protrusion relative depth increases. The average Nusselt number increases with protrusion relative depth and jet Reynolds number. For most of the cases, both heat transfer enhancement within the stagnation region and increase of heat transfer area result in overall heat transfer improvement of the jet impingement with protrusioned target surface. (C) 2012 Elsevier Ltd. All rights reserved.