One-dimensional transient model for fluid flow and heat transfer is presented for a micro-grooved heat pipe of any polygonal shape utilizing a macroscopic approach. The coupled non-linear governing equations for the fluid flow, heat and mass transfer are developed based on first principles and are solved simultaneously. The transient behavior for various parameters, e.g. substrate temperature, radius of curvature, liquid velocity, etc. are studied. The effects of the groove dimensions, heat input and Q-profiles on the studied parameters have been evaluated. The steady state profiles for substrate temperature, radius of curvature, liquid velocity etc. have also been generated. The model predicted steady state substrate temperature profile is successfully compared with the experimental results from the previous study. The general nature of the model and the associated parametric study ensure the wide applicability of the model. (c) 2004 Elsevier Ltd. All rights reserved.