The Tafel slopes are calculated at 5 mV/s scan rate at the HER onset potential region in argon saturated electrolytes. A Tafel slope of ~ 57 mV/decade (mV/dec) was obtained for HER in 0.1M KOH, in good agreement with previous reports. The Tafel slope increases with increasing KOH concentration up to a value of ~ 114 mV/dec in 6M KOH. The increment in the Tafel slope indicates a change in the HER kinetics and it can be attributed to the changes in the rate determining step. It can be assumed that the rate determining step of the HER on Pt changes from the transfer of a proton and an electron to an adsorbed H (Heyrovsky step in 0.1M KOH) to the adsorption of H + (Volmer step in 6M KOH), which is attributed to the changes in water dissociation energy, as discussed later. According to the HBE hypothesis, the apparent ΔEM-H can be calculated from analyzing the cyclic voltammogram (CV) of Pt using the relation ΔE MH = FEpeak, where F is the Faraday constant and E peak is the potential of Pt (100) or (110) H UPD peaks. It has to be noted that in contrast to a high acidic medium, water plays an important role to generate H + /*H in low acidic, neutral, and alkaline media. It has been identified that water can be mainly in three different co-ordinations environments (namely tetrahedrally coordinated, trihedrally coordinated, and free water) in an electrolyte depending upon the degree of hydrogen bonding within the solution. As the degree of hydrogen bonding of water increases, the activation energy required for its dissociation increases in the order: