We show, by use of self-consistent Monte Carlo simulations, that contact between a liquid metal and a polar adsorbate alters the longitudinal density distribution in the liquid metal side of the interface. In particular, the amplitude of modulation of the stratification of the metal in the interface is increased by the polar adsorbate, which will lead to changes in the work function, transverse electrical conductivity, etc. The results of calculations of the x-ray reflectivity as a function of angle of incidence on the liquid metal–polar adsorbate interface suggest that the change induced in the interface longitudinal density distribution of the metal is measurable.