In this study, direct current (DC) conductivities in the system which was composed of ahe clay fraction(<2 p) of variable charge soil and electrolyte solution with a concentration of 0.35×10^-4-1.3×10^-4 mol/L were measured within the range of 5-50℃. The results showed that heated conductivity dispersion could be used for investigating interactions between ions and the clay fraction of soils. The temperatures at turning points on DC conductivity-temperature curves varied with the content of water, kind of electrolytes, and type of soils. At the same content of water, the temperatures at turning points for the sysrem of red earth containing different electrolytes were in the sequence of CaCl₂ > Na₂SO₄ > KCl > Ca(NO₃)₂ > NaNO₃. The temperatures at turning points for latosol system were apparently higher than chose for red earth system. The difference in temperatures at turning points is interpreted in terms of the strength of the interaction between the ion and the clay particle.