Electronic cooling has been a rising issue mainly due to the rapid development of high-throughput computing in data centres as well as battery energy storage, which release huge amount of heat through compact surfaces. The electronic cooling process is not only energy-intensive but also difficult to control. This paper proposes an effective cooling method for electronic devices by integrating phase change materials (PCMs) with three-dimensional oscillating heat pipes (3D-OHPs), where PCMs are used to store heat dissipated by the electronic device and 3D-OHPs to fast transport the stored heat from PCMs to the environment. A novel leaf-shaped structure is designed for the 3D-OHPs. Experimental study is carried out on the leaf-shaped 3D-OHPs with various working parameters including cooling air velocity, wind direction and heat input. Further, the leaf-shaped 3D-OHPs are embedded into PCMs to cool down the electronic devices. Temperature variations and thermal resistance are evaluated and compared with the conventional air cooling method. The experimental results indicate that the surface temperature of electronic devices can be well controlled below 100 degrees C, which is similar to 35 degrees C lower than that with conventional air cooling. The thermal resistance is decreased up to 36.3%. The 3D-OHPs with a filling ratio of 34-44% achieve the best thermal performance. What's more, the leaf-shaped structure of the 3D-OHPs contributes to a similar to 2 degrees C lower temperature on the electronic device's surface than the typical used 3D-OHPs. This research will promote the development of effective cooling for electronic devices. (C) 2020 Elsevier Ltd. All rights reserved.