The adsorption of sodium polystyrene sulfonate (PSSNa) on TiO2in aqueous dispersion has been investigated in pure water and in the presence of different concentrations of sodium sulphate. The stability of TiO2dispersions in PSSNa and Na2SO4solutions has also been studied. Correlation between adsorption isotherms,zeta potential data and stability measurements has shown that the specific adorption of sulphate anions influences the adsorption of PSSNa and then the stability of the dispersions. The adding of proper amounts of Na2SO4increases the stability of TiO2dispersions in PSSNa solutions.