Selective electrochemical reduction of CO2 to CO was studied using a new electrocatalyst and a gas-electrolysis cell utilized a polymer-electrolyte-membrane (PEM) reactor. A selective and active electrocatalyst was prepared by partial pyrolysis of electrocatalyst precursor of Co-4,4'-dimethyl-2,2'-bipyridine (4,4'-dmbpy) supported on Ketjenblack (KB). A heat-treatment temperature of the Co-4,4'-dmbpy/KB significantly influenced on its electrocatalytic activity and 573 similar to 673 K treatments were suitable for a selective CO2 reduction. A high performance of CO formation (331 mu mol h(-1) cm(-2), 217 TOF(Co) h(-1)) at 20 mA cm(-2) with 72% faradic efficiency was performed by using the optimized Co-4,4'-dmbpy/KB electrocatalyst at -0.75 V (SHE) and 273 K. Electrochemical silent Co species in CV studies promoted electrochemical reduction of CO2 to CO.