A model for the fluid flow and heat transfer in an electrohydrodynamically (EHD) augmented micro-heat pipe is presented utilizing a macroscopic approach. Coulomb and dielectrophoretic forces have been considered in the model. The coupled non-linear governing equations for the fluid flow, heat and mass transfer are developed based on the first principles and are solved numerically. The effects of Coulomb and dielectrophoretic forces have been studied together and the effects have been compared. The analytical expressions for the critical heat input and for the dry-out length have been obtained, which show that with an increase in the electric field intensity, the critical heat input increases and the dry-out length decreases. It is found that using EHD, the critical heat input can be increased by 100 times. The contribution of Coulomb force is observed stronger than that of dielectrophoretic force. Also, the critical heat input and the dry-out length have been successfully compared with the experimental results available in the literature. The general nature of the model and the associated parametric study will be useful to understand the EHD pumping in a micro-heat pipe. (c) 2006 Elsevier Ltd. All rights reserved.