Table shows the TONs (Turnover Numbers) and FEs (Faradic Efficiencies) obtained for all the different conditions tested. TONCO, TONH2 and corresponding FE values were obtained by sampling gases from the cell headspace every 5 minutes and by injecting them in a micro-GC analyzer, while TONHCOO-and FEHCOO-were evaluated by quantitative 1 H NMR analysis of the catholyte at the end of electrolysis. Figure displays the overall TONH2, TONCO and TONHCOO-values after 22 hours of continuous CPE at -1.35 V for all amines (Ered=-1.35 V, TBAPF6 0.1 M), and the production of H2 and CO over time of a methanolic solution containing PMDETA. Some general observation can be made from the results gathered in Figure and Table . We previously reported that the same Mn/CC catalyst only afforded CO (FECO = 60%) and H2 (FEH2 = 40%) as CO2 reduction products when used in aqueous medium, while CPE in MeOH displays FECO = 51%, FeH2 = 20% and FEHCOO-= 26% (Table ). It is now accepted that the production of formate occurs via the formation of the hydride HMn intermediate, while CO2 reaction with the active catalysts Mn -, followed by the protonation-first or reduction-first mechanisms lead to CO (Scheme 2). Clearly, by simply switching from aqueous to methanolic solutions, a change in reduction selectivity occurs. The same shift in selectivity in favour of formate (path via HMn -in Scheme 2) may be obtained in water by using gas diffusion layer (GDL) electrochemical cell, resulting into FECO = 76.2%, FEH2 = 13.7% and FEHCOO-= 10.1%. The effect has been ascribed to acidification induced by increased CO2 concentrations, symptomatic of GDL cells. Following this track, we tried to further shed light on the chemical process leading to formate production in methanol. This may either be imputed to higher CO2 concentration (as in water ) and, when any, to a noninnocent-role played by the amine in the catalytic reduction mechanism.