The application of an electric field on soil mass induces both electro-osmotic flow and electro-migration, which has been used for the dewatering of soft soils and remediation of contaminated soils. The physical and chemical properties of soft soils are influenced by the soil pH as well as ionic species and their concentrations, which subsequently influence the dewatering and remediation efficiency. In the present study, one-dimensional column experiments were conducted to investigate the influence of soil pH and ionic species on the electro-osmotic consolidation process of kaolin. The initial drainage rate, total volume of the discharged water and the voltage loss near the anode increased with the increase in the initial soil pH. After electro-osmosis, the water content was lower near the anode and higher near the cathode for sample with higher initial soil pH. The addition of copper ions reduced the dewatering efficiency while the addition of sodium ions increased the drainage rate and total volume of discharged water. Moreover, the precipitation of copper ions increased the voltage loss near the cathode.