The formal potentials and kinetic parameters for the electrode process Cr2+ + 2e(-)reversible arrow Cr-0 occurring at mercury electrode in solutions of LiClO4 + LiCl (a(H2O) = 0.741) and LiClO4 + LiI (a(H2O) = 0.853) were determined from analysis of irreversible anodic and cathodic chronocoulometric charge-potential curves. The interaction of Cr(II) with I- ions was found to be stronger (K-1 = 1.6 M(-1)) than the very weak interaction with Cl- ions (K-1 < 0.1 M(-1)). Double-layer properties were established for the solutions studied. On the basis of the rate constants, transfer coefficients, electrode reaction orders, double-layer properties and charges of the activated complex determined, a mechanism for the electrode reaction of the Cr2+/Cr(Hg) redox couple was proposed.