The laminar convective heat transfer and pressure drop characteristics in tree-like microchannel nets are numerically investigated and compared to the corresponding characteristics in traditional serpentine flow patterns, by solving the Navier-Stokes and energy equation for an incompressible fluid with constant properties in three dimensions. A constant heat flux is applied to the walls of the square cross-sectional channels. The intrinsic advantage of tree-like nets with respect to both heat transfer and pressure drop is demonstrated. In addition, secondary flow motions initiated at bifurcations and their important role on thermal mixing are identified and discussed. Thermal management issues in polymer electrolyte fuel cells are addressed and in this context, the future employment of tree nets is recommended. (C) 2004 Elsevier B.V. All rights reserved.