Conductometric studies have been made for the persulphates of sodium, potassium, and ammonium in water and water + acetone (X-acetone = 0.016, 0.033, 0.072, 0.117 and 0.171) mixtures at 298.15, 303.15, 308.15 and 313.15 K, using Shedlovsky and Fuoss-Kraus extrapolation techniques. The limiting molar conductance (Lambda(o)), association constant ( K-A), Walden product (Lambda(o)eta(o)) and the thermodynamic functions for the process of ion-pair formation have been evaluated and discussed.