Accurate determination of thermal conductivity can be achieved through measurements of soil parameters which are strongly coupled to thermal conductivity. One such parameter is soil dielectric permittivity or conductivity. Several researchers, De Vries 1963 [1], Tarnawski 2000 [2] and Archie 1942 [3], have shown that both the thermal conductivity and dielectric permittivity or conductivity of soil depend on same parameters such as chemical composition, soil structure, and hydro-mechanical properties. In this research, the relationship between thermal conductivity and dielectric permittivity of soils was theoretically and experimentally studied. For this purpose, the thermal conductivity and dielectric permittivity of three silty clay soils, with known chemical and hydro-mechanical properties, were studied simultaneously under varying conditions of soil moisture. As expected, strong correlations between thermal conductivity and dielectric permittivity were obtained.