In the past, several hypothesis have been put forward to explain the pH dependency of HER kinetics on Pt. It was initially suggested that the stronger PtH binding energy in alkaline media, which can be corelated to shifts in the H UPD peaks with pH, is the sole reason for the slower rate of HER in alkaline electrolytes., However, it was later shown that the ΔE M-H is an inherent property of a metal, and the variations in H UPD peak positions are due to the competitive mechanism between *H and water adsorption, where the latter becomes weaker at high alkalinity. Alternatively, 'specific adsorption of cations and their different capability in stabilizing/destabilizing *OH' has also been proposed as the origin of shift in the H UPD peaks. In a different work, the binding energy of PtH2O instead of PtH binding energy was taken considered to explain the pH dependent HER kinetics of Pt in a highly alkaline medium. According to this hypothesis, the PtH2O binding energy decreases with increasing pH of the electrolytes whereas the apparent PtH binding energy increases, leading to the slower kinetics of HER of Pt in alkaline medium. According to Markovic et. al., the slower kinetics of Pt towards HER in alkaline medium is due to the high energy barrier for the dissociation of water to generate H ad . According to them, the energy barrier to dissociate water can be minimised by using Ni(OH) 2 coated Pt, while the reason behind the high activation energy for water dissociation in alkaline medium was not known. According to a different hypothesis, because the potential of zero free charge (pzfc) of Pt is pH independent, the HER of Pt shifts further away from the pzfc of Pt with increasing pH, making the water reorganization difficult at the interface. Lin-fan Shen et. al. have shown that the pHdependent kinetics on Pt surfaces and the Ni-induced high activity are driven by the structure of the interfacial water. It was shown by in situ Raman studies that, although the water structure does not get affected by the applied potential in an acidic medium, the population of different water co-ordinations in Pt and Pt-Ni are different in an alkaline medium. It is shown that 'free-water' type (dangling O-H bonds) is available in Pt-Ni-0.1M NaOH system while almost no such water co-ordination is available in Pt-0.1M NaOH system at a similar potential. This has been correlated to the higher activity of Pt-Ni in alkaline medium in comparison to the sluggish activity of bare Pt electrode.