Cobalt phthalocyanine can effectively convert CO2 or CO to methanol. However, this reaction is hampered by low selectivity (a methanol Faradaic efficiency of less than 40%) and poor understanding of the kinetics and mechanism. In this work, we use a mechanism-guided reaction design approach based on systematic kinetic studies to overcome these limitations. pH-dependent Tafel analysis and kinetic isotopic effect experiments explain that methanol production from CO electroreduction is pH independent and limited by the *CO hydrogenation to *CHO step with H2O as the major proton source. Proton donor comparisons show that bicarbonate can promote the reaction at its optimal concentration of 0.1 M and CO reaction order studies confirm a Henry type isotherm for CO adsorption on the catalyst surface.