Reduction potential of Hydrogen electrode is minimum when it is in contact with 

$\begin{array}{l}{\mathrm{E}}_{H^{+}/\frac{1}{2}{\mathrm{H}}_2,\mathrm{Pt}}= {\mathrm{E}}^0+\frac{0.0591}{1}\text{l}\mathrm{og}\left[{\mathrm{H}}^{+}\right]\\ {\mathrm{E}}_{\mathrm{RP}}\propto \text{\hspace{0.17em}l}\mathrm{og}\left[{\mathrm{H}}^{+}\right]\end{array}$

Reduction potential is minimum when dipped in 0.001M HCl