Abstract: Phosphoric acid and its acidic sodium salts are unsymmetrical electrolytes. There exist dissociation and association equilibria among the species of these electrolytes in aqueous solutions. The molar conductivity of solution is equal to the sum of the ionic contributions. The molar conductivities of the solution and relevant ions were calculated respectively by using a new prediction equation of ionic conductivity proposed in a previous paper of the authors.The results calculated from the new equation were in good agreement with those from literature and the four-parameter Quint-Viallard’s conductance equation.