Copper nanoparticles were electrodeposited in situ on a conductive multi-walled carbon nanotubes (MWCNT) support at a free-standing water/1,2-dichloroethane interface. The Cu/MWCNT nanocomposites act as highly active hydrogen evolution catalysts at the interface in the presence of lipophilic decamethylferrocene as the reducing agent. Liquid assets: In situ electrodeposited Cu/multi-walled carbon nanotube (MWCNT) nanocomposites act as highly active hydrogen evolution catalysts at the liquid/liquid interface in the presence of lipophilic decamethylferrocene as the reducing agent.