Аннотация:On the basis of electrocapillary measurements, the values of the specific adsorption of Fe(CN)//6**4** minus anions at the Hg/H//2O interface were calculated in the region of charges from 2 to 14 mu C/cm**2 and in the range of K//4Fe(CN)//6 concentrations from 0. 005 to 0. 25 m. The results obtained can be described both by the virial isotherm without correction for the drop in the potential in the diffusion portion of the double layer and by the virial isotherm considering this correction; however, in the latter case the agreement between calculation and experiment is better.