Abstract: The interfacial capacity-potential curves of Hg,Cd(Hg)and Pb(Hg)electrodes and the desorption potentials" on the three electrodes in₁₂ typical surface-active organic substances in₁M KC₁ were measured by DD-1 typle electroplate parameter measurement meter.As anodic soluble potentials of Cd(Hg)and Pb(Hg)electrodes are more negative,the desorptions F^-,Cl^-,Br^-were not found.It was found that the sequence of surface activities of I-and the surface activities of same surface-active substances on the three electrodes usually follow Hg>Pb(Hg)>Cd(Hg).Given results show.The difference of desorption potentials on the three electrodes in same concentration and same surface-active substances was less 10mV.It was showed that the surface characters of Cd(Hg)and Pb(Hg)at the desorption potentials were as same as that of Hg.