The paper proposes a technique of using micro-W-shaped ribs on a test plate to improve the impingement heat transfer performance in a multiple-jet impingement cooling system. A combined experimental and numerical investigation has been conducted on the heat transfer characteristics of multiple jet impingement on a flat plate and a roughened plate with micro W-shaped ribs under maximum crossflow scheme. The jet-to-plate spacing of H/D = 1.5 was used in the impingement systems with both the flat plate and the micro-W-rib roughened plate. Transient liquid crystal thermography method has been used in the experiments to obtain detailed heat transfer distribution on the test plates for the Reynolds numbers ranging from 15,000 to 30,000. The experiments showed that the micro W ribs can improve the areaaveraged impingement heat transfer on the test plate by about 9.6% at a Reynolds number of 30,000, and the pressure loss is negligibly increased compared to the impingement on the flat plate. In addition, numerical computations have further been done to examine more flow and heat transfer details in the impingement system with the micro-W-rib roughened plate. The comparisons between the experimental and numerical data showed that the numerical computations can well predict the impingement heat transfer patterns on the micro-W-rib roughened plate. (C) 2015 Elsevier Ltd. All rights reserved.