Replacement of precious metal electrocatalysts with highly active and cost effi cient alternatives for complete water splitting at low voltage has attracted a growing attention in recent years. Here, this study reports a carbon-based composite co-doped with nitrogen and trace amount of metallic cobalt (1 at%) as a bifunctional electrocatalyst for water splitting at low overpotential and high current density. An excellent electrochemical activity of the newly developed electrocatalyst originates from its graphitic nanostructure and highly active Co-N x sites. In the case of carefully optimized sample of this electrocatalyst, 10 mA cm −2 current density can be achieved for two half reactions in alkaline solutions—hydrogen evolution reaction and oxygen evolution reaction—at low overpotentials of 220 and 350 mV, respectively, which are smaller than those previously reported for nonprecious metal and metalfree counterparts. Based on the spectroscopic and electrochemical investigations, the newly identifi ed Co-N x sites in the carbon framework are responsible for high electrocatalytic activity of the Co,N-doped carbon. This study indicates that a trace level of the introduced Co into N-doped carbon can signifi cantly enhance its electrocatalytic activity toward water splitting. ; Bita Bayatsarmadi, Yao Zheng, Youhong Tang, Mietek Jaroniec and Shi-Zhang Qiao