One can observe under potential (H UPD ) or over potential deposited (H OPD ) hydrogen presence in alkaline medium too by applied potential controlled surface enhanced spectroscopy with surfaces like Pt. Due to the limited availability of protons in low acidic conditions, water is a more likely source of adsorbed hydrogen, and the dissociation energy of water adds an extra contribution to the Gibbs free energy of the Volmer step (H 2 O + e -→ *H +OH -). Hence, the rate determining steps of HER are different in alkaline and acidic electrolytes, and a clear understanding of the mechanism is essential for the designing of next generation cost effective catalysts for this process.