The isomerization of 2-3-dimethyl-1-butene was enhanced over a thousand fold (vs the open circuit value) by spillover protons generated by low currents (electrochemical promotion) on carbon supported Pd catalysts in a polymer electrolyte fuel cell. There was substantial proton spillover catalyzed shift of the double bond of 2-3-dimethyl-1-butene. With 3-3-dimethyl-1-butene, the proton spillover catalyzed methyl shift occurred at low levels and 2-2-dimethyl-butane was the primary product from the simple reduction reaction. Although the substantial non-Faradaic electrochemical modification of catalysis (NEMCA) of the double bond isomerization of an olefin was further demonstrated, the more challenging electrochemical promotion of an olefin methyl shift at the polymer electrolyte Pd/C cathode was less pronounced.