In this work, the catalytic activities of electrodeposited Ag and Agin bimetallic dendrites have been explored for electrochemical reduction of CO2 to CO. In the case of Ag dendrites, the Ag crystal structure was found to be affected by the deposition potential and showed different Ag(220)/Ag(111) ratios. The Faradaic efficiencies to produce CO increased as this ratio increased, whereas the partial current densities for CO generation were found to have a stronger relationship with the roughness of the Ag catalyst. The electrodeposition of Agin was carried out to investigate the effect of addition of In and its content on the catalytic performance, while maintaining the dendritic morphology. The crystal structures of Agin dendrites were found to vary with the amount of added In, demonstrating a linear increase in the ratio Ag(220)/Ag(111) with increasing In content and a positive impact on the production of CO. Furthermore, there was a competition between the suppression of the hydrogen evolution reaction (HER) vs. the decrement in the amount of active Ag with increasing addition of In. It was found that these complementary effects resulted in a superior CO Faradaic efficiency of Agin dendrites with a volcano shaped curve based on the In content. The complementary effect on the catalytic activity could be extended to the various reduction potentials, indicating the significant effect of HER suppression at highly negative reduction potentials. (C) 2017 Elsevier B.V. All rights reserved.