Аннотация:Chloride ion adsorption was studied by differential-capacitance measurements at the Hg/H//2O interface in x M NaCl plus 0. 1 M NaF solutions where 10** minus **4 less than equivalent to x less than equivalent to 0. 1. The experimental data were compared with data obtained from the double-layer models of Grahame and Parsons (GP) and Alekseev, Popov, and Kolotyrkin (APK). It was shown that under conditions where the compact-layer capacity is independent of surface coverage, as in the system examined, it is not possible to make the choice between the GP and APK model.