The transport of singly and doubly charged cations of metals (Tl+, Cd2+, and Pb2+) was studied in solutions of the polyelectrolyte poly(styrenesulfonic acid), PSSA, by voltammetric measurements at a mercury film disk microelectrode in solutions of various ionic strengths. Metal cations present in concentrations much lower than the equivalent concentration of polyacid were used as probe counterions. The interactions between counterion and polyelectrolyte were evaluated by the ratio of diffusion coefficients in the solution with and without polyelectrolyte, D-PSSA/D-o. These interactions were found to be much stronger for the doubly charged metal cations than for the singly charged counterions. The ratio of D-PSSA/D-o was 0.06 for lead and cadmium counterions and 0.35 for the thallium counterion. This ratio obtained for thallium cation in poly(styrenesulfonic acid) was very close to that found previously for hydrogen counterion in PSSA solution, 0.345. The transport of metal probe counterion was also studied in solutions of the sodium salt of poly(styrenesulfonic acid). The dependence of the diffusion coefficient of metal cations on concentration of supporting electrolyte was studied over a wide range of ratios of metal cation concentration to polyelectrolyte concentration and over a wide range of concentrations of supporting electrolyte.