In this study, we systematically investigate the role of chloride ions on Cu-Sn electrodes (copper tin chloride, CTC) for ECR. First, we experimentally evaluate the influence of adsorbed chloride by functionalizing the Cu2O surface via SnCl4 deposition and analyse its effect on ECR activity and product selectivity. Special attention is given to ethane formation, examining how chloride anions influence C-C bond formation and hydrogenation pathways.