We have studied the LME phenomenon for the Cu/Hg couple, from an experimental and a computational point of view. We compared the LME behavior of standard oxygen free high conductivity (OFHC) copper with Grain Boundary Engineered (GBE) copper (containing a high fraction of special Σ3 GBs). Experimentally, we find that special Σ3 GBs in copper are less prone than general GB to LME by liquid mercury. In parallel, we have investigated the difference in LME induced fracture between the symmetric Σ3(111)70.5° tilt GB and the symmetric Σ5(210)36.87° tilt GB by ab-initio calculations. The Hg segregation trend has been evaluated for these 2 GBs. Ab-initio tensile tests on the Σ3(111) GB with and without segregated Hg atoms have been performed. Finally solid/liquid interfaces have been modeled using ab-initio molecular dynamics (AIMD) in order to calculate solid-liquid surface energies (γSL). Using a Griffith approach, we have evaluated the energy difference γGB - 2 γSL. The LME mechanism in Cu/Hg is discussed.