This study presents an optimization procedure for the design of a Latent Heat Thermal Management System (LHTMS), used for cooling an electronic device with transient and high heat generation. The LHTMS consists of Phase Change Material (PCM), combined with internal fins, which are used for creating high conductive paths into the PCM. The optimization is performed with a sole aim of minimizing the LHTMS height, while still maintaining the capability of absorbing the heat generated by the electronic device, and without exceeding the maximum allowable temperature. Two dimensional, three-parametric, finite element (FEM) simulations are performed, with systematically varying both the number and thickness of the fins under several LHTMS heights. The optimized results of this study are presented and discussed, emphasizing the derived optimal PCM percentages, which are an essential parameter in designing an LHTMS. These results show that optimal PCM percentages depend on the number and the length of the fins, the heat flux at the interface, and the difference between the critical and liquidus temperatures of the PCM. (C) 2013 Elsevier Ltd. All rights reserved.