An analytical solution for both the liquid and vapour flows inside a flat micro heat pipe (MHP) coupled to an analytical solution for the temperature inside the MHP wall is presented. The maximum heat transfer capability of a flat MHP, on which several heat sources and heat sinks are located, is calculated. The capillary structure inside the MHP is modeled by considering a porous medium, which allows to take into account capillary structures such as meshes or sintered powder wicks. The thermal model is able to calculate the part of heat flux transferred only by heat conduction in the MHP wall from the heat transferred by change of phase. (c) 2005 Elsevier Ltd. All rights reserved.