We report here the first pure organometallic fac-[MnI(CO)3(bis-MeNHC)Br] complex with unprecedented activity for selective electrocatalytic CO2-to-CO reduction, exceeding 100 turnovers CO with excellent faradaic yields (ηCO ~ 95%) in anhydrous CH3CN. Under the same conditions, a maximum turnover frequency (TOFmax) of 2100 s-1 was measured by CV, clearly higher than the values reported for other Mn based catalysts. Moreover, the addition of water produces the highest TOFmax (~320000 s-1) reported for a Mn based catalyst. A MnI tetracarbonyl intermediate is for the first time detected under catalytic conditions.