In this paper, the heat transfer characteristics of a phase change material (PCM) based heat sink using structured porous media (specifically Lattice Frame Materials (LFMs) and honeycomb structures) as thermal conductivity enhancers (TCE) are numerically investigated and compared against that of pure PCM without any enhancers. A three-dimensional transient simulation is performed using the finite-volume method and the phase change process is modelled with the enthalpy-porosity formulation. In addition the effect of various parameters like configuration and porosity of the structured porous media, on the thermal performance of the heat sink is determined. The distribution of input heat into the sensible and latent components is also studied. Furthermore the behaviour of the proposed heat sink under different usage conditions (heavy, light and frequent) and in discharging is also observed. Finally a parametric study on the optimum quantity of PCM required inside the heat sink is performed to understand the influence of various different factors on the optimum quantity of PCM; and a dimensional analysis is performed to generalize the results. © 2016 Elsevier Masson SAS.