Abstract: The behaviour of the Nickel(Ⅱ) ion in the presence of dimethyl-glyoxime (DMG) on the hanging mercury drop electrode in NH_3/NH_4Cl media was investigated with different electrochemical techniques. It was found that: (1) the reactant was Ni(Ⅱ) complex with DMG, Ni(Ⅱ)A_2, adsorbed on the electrode surface; (2) the intermediate was Ni(Ⅰ)A_2 and (3) the product was metal amalgam Ni(0)(Hg). Two electrons were transferred in the overall reaction and the transfer coefficient was 1.8 which was measured experimentally. From experimental results, it was obvious that the reaction orders with respect to Ni(Ⅱ), DMG and H~+ were 1,2, and 1, respectively. A new compound, X, was detected. The reaction scheme could be written as follows
Ni(Ⅱ)A_2+Hg<=>Ni(Ⅱ)A_2(ads)(Hg)
Ni(Ⅱ)A_2(ads)(Hg)+e~-<=>Ni(Ⅰ)A_2(ads)(Hg)
Ni(Ⅰ)A_2(ads)(Hg)+H~++e~-→Ni(0)(Hg)+HA(des)+A~-(des)
→X+Hg