This paper discusses two advanced heat pipe mechanisms that have the potential of achieving heat flux capabilities over 300W/cm2. The mechanisms include Combined Pulsating and Capillary Transport (CPCT) and Graded Wick Transport (GWT) mechanisms. Theoretical models were developed to predict the performance of the advanced heat pipe mechanisms. Prototype heat pipes were tested to verify the heat flux capability of the mechanisms and the accuracy of the theoretical models. The advanced heat pipe mechanisms are feasible approaches to removing increasing heat dissipation densities in electronic equipment.