For all electrocatalysts (even Pt), the kinetics of the hydrogen evolution reaction (HER) in alkaline environments are more sluggish by a factor of two to three compared to those in acidic solutions. Here, we demonstrated the preparation of a novel ruthenium/nitrogen-doped carbon (Ru/NC) electrocatalyst supported by graphite foam, in which abundant, singly dispersed Ru atoms were chelated to a nitrogen-doped carbon matrix. In a 1 M KOH aqueous solution, the resultant Ru/NC electrocatalyst exhibited excellent electrocatalytic HER activity with an extremely low overpotential of only 21 mV at 10 mA cm^-2 and an excellent mass current density as high as 8 A mg_Ru^-1 at 100 mV, which is superior to the values for reported electrocatalysts (overpotentials of >50 mV at 10 mA cm^-2), even Pt catalysts (overpotential of ∼36 mV at 10 mA cm^-2). Importantly, the inherent turnover frequency (TOF) value (per Ru atom) of the Ru/NC electrocatalyst reaches 4.55 s^-1, which is 3.2 times higher than that of the Pt catalyst (1.41 s^-1). Electrochemical analyses and structural characterization revealed that atomically dispersed Ru is responsible for the outstanding HER activity of the Ru/NC electrocatalyst because of a substantially accelerated Volmer step. The outstanding HER performance gives the Ru/NC electrocatalyst promising potential for practical hydrogen production applications.