WS 2 , which is composed of cheap and earth-abundant elements, catalyzes the hydrogen-evolution reaction efficiently using the organic electron-donor decamethylferrocene. This catalytic activity has been investigated at liquid-liquid interfaces (water-1,2-dichloroethane) by voltammetry and biphasic reactions observed by UV/Vis spectroscopy and GC. It's all about HER: WS 2 is an efficient catalyst for the hydrogen-evolution reaction using organic electron donors such as decamethylferrocene. This catalytic effect is proven by GC, UV/Vis, and cyclic voltammetry. DCE=1,2-dichloroethane; DMFc=decamethylferrocene.