The 2,2’-bi-1H-imidazole (H2BIM(0)) can change to 2,2’-bi-1H-imidazolium (H4BIM(2+)) by the two-step proton-transfer, then, to 2,2’-bi(2,3-dihydroimidazolylidene) (H4BIM(0)) by the two-step electron-transfer. From the systematic investigations of half-wave redox potentials (E(1/2)) and acid dissociation constants (pK(a)), we estimated the repulsion energy of electrons (U-1(CT)) and protons (U-1(PT)) for H4BIM(0) and H4BIM(2+), respectively, and other systems, p-benzoquinones (BQs), diphenoquinones (DPQs), 7,7,8,8-tetracyanoquinodimethanes (TCNQs), tetrathiafulvalenes (TTFs), aromaticdiamines, hydroquinones (H2Qs), 1,4-benzenedimalononitrile (H2TCNQ), bis(4-hydroxyphenyl) sulfides (HPSs). The U-1(CT) and U-1(PT) values are deduced from the linear correlation between the first E(1/2)(1) (pK(a1)) value and the second E(1/2)(2) (pK(a2)) one. The obtained U-1(CT) of H4BIM(0) (4.68 eV) is comparable to that of TTF (4.65 eV), and U-1(PT) of H4BIM(2+) (4.26 eV) is slightly larger than that of H2TCNQ (4.22 eV). The U-1(CT) and U-1(PT) values are correlated to the structural parameter of pi-electron density and molecular length.