In the present study, a topology optimization approach is proposed to determine an optimal geometry of a wick sintered inside a flat plate heat pipe. Total thickness of the heat pipe is assumed as fixed, and thus the task involves redistributing the wick material and selecting the internal shape of the vapor core to provide a minimum power dissipation in the liquid flow and minimum total pressure drop in the entire heat pipe. Constraints are used for the maximum volume of the wick and maximum allowable temperature of the heat pipe wall. With respect to the preliminary assessments, the simulations are realized based on simplified 2D steady state thermal and hydrodynamic models assuming constant temperature and laminar flow in the vapor core and Darcy's law for the liquid flow through the porous wick. Optimization results are presented for rectangular flat heat pipes with different lengths and thicknesses. Optimal placement of the wick columns and grooves are obtained by using the proposed topology optimization scheme. The results indicate that the use of the wicks of optimal shape increases the operating performance of flat heat pipes and especially increases their heat transfer capability up to twice that of heat pipes with flat wicks of constant thickness. (C) 2018 Elsevier Ltd. All rights reserved.