A mononuclear Co(II) derivative, (1) is afforded by employing a 'scorpionate' type precursor, bdtbpza [bdtbpza = bis(3,5di- t-butylpyrazol-1-yl) acetate]. Single crystal X-ray structure reveals that the -CoII ion exhibits an octahedral geometry possessing on a -O6 coordination environment. Detailed EPR interpretation and electrocatalytic hydrogen evolution study are reported. Electrochemical and catalytic study of 1 in DMSO with the presence of acetic acid as weak proton source shows an observed rate constant of 3.7 x 103 s-1 and hydrogen evolution Faradaic efficiency of 74.7%. The catalytic process requires two-electron reduction of the catalyst and formation of a cobalt(II)-hydride species as reactive intermediate. [GRAPHICS] .