Active and capacitive resistances of graphite electrode in the borosilicate melts (Na2O·B2O3·SiO2 or 2SiO2) are measured at various frequencies of alternating current of low amplitude. An equivalent electric circuit of phase interface is revealed and its parameters are determined. The dependences of adsorption capacity upon graphite electrode potential in the melts, having different basics, are found. Effect of temperature and pressure on the characteristics of adsorption process is investigated.