The ECH of maleic acid showed that it is possible to selectively hydrogenate C=C bonds by Cu. Therefore, we decided to investigate the selective ECH of the C=C in an α,β-unsaturated ketone, a challenging goal in organic electrosynthesis. With this aim, the ECH of cyclohex-2-en-1-one was explored under the same reaction conditions as for maleic acid, except the potential which was optimized to -0.58 VRHE. After 1 h electrolysis, 24% of the reactant was converted, affording 22% of the desired C=C hydrogenation product (i.e. cyclohexanone) and only ca. 1% of the further hydrogenated product (i.e. cyclohexanol; see NMR spectra in Supplementary Figure ). After 6 h of electrolysis, a remarkable conversion of 88% was achieved, split into 77% yield of cyclohexanone and 10% yield of cyclohexanol (Fig. and Supplementary Figure ). Hence, these results demonstrate the excellent chemoselectivity of this ECH process. We speculate that the extended d orbitals present in copper allow for an effective soft-soft interaction with the C=C p-bond selectively hydrogenating the olefin in α,β-unsaturated ketones whilst preserving the harder carbonyl groups. The substrate scope on the Cu electrocatalyst was further extended to the ECH of C≡C triple bonds, namely the hydrogenation of phenylpropiolic acid (Fig. . NMR spectra and temporary changes of concentrations can be found in Supplementary Figures ). The selective hydrogenation of C≡C to C=C (instead of the complete hydrogenation to C-C) is a major challenge in alkyne reduction in general.(17) Importantly, after 2 h of controlled potential electrolysis, 24% of the alkyne was converted into 21% of the corresponding alkene (i.e. cinnamic acid) and only ca. 0.5% of the alkane product (i.e. phenylpropanoic acid), while after 12 h, a total conversion of 82% was achieved with 76% and 7% of the alkene (a mixture of E/Z products) and alkane products, respectively. While excellent selectivities have been reported for the ECH of acetylene using a LDH-derived Cu catalyst and electrochemically deposited Cu dendrites, our findings show both remarkable selectivity and chemoselectivity.