Hydrogen evolution at polarized liquid-liquid interfaces [water/1,2-dichloroethane (DCE)] by the electron donor decamethylferrocene (DMFc) is catalyzed efficiently by the fabricated cobalt sulfide (CoS) nanoparticles and nanocomposites of CoS nanoparticles formed on multi-walled carbon nanotubes (CoS/CNT). The suspended CoS/CNT nanocomposite catalysts at the interface show a higher catalytic activity for the hydrogen evolution reaction (HER) than the CoS nanoparticles due to the high dispersity and conductivity of the CNT materials, which can serve as the main charge transport pathways for the injection of electrons to attain the catalytic sites of the nanoparticles. The reaction rate increased more than 1000-fold and 300-fold by using CoS/CNT and CoS catalysts, respectively, when compared to a non-catalyzed reaction.