It is possible to determine the standard reduction potential of half cell by using hydrogen electrode as a reference electrode.
The standard oxidation potential of hydrogen half cell, under standard conditions, is 0 v. Hence, when an unknown half cell (say X/X-) is clubbed with hydrogen half cell, it directly gives the half cell potential of electrode of interest.
Such electrochemical cell can be represented as follows:
Pt/H2/H+//X-/X
Here, Eo cell = Eo X/X- - Eo H2/H+
But, Eo H2/H+ = 0 V
∴ Eo cell = Eo X/X-
