The thermal properties of three soils have been studied to ascertain the effects of saturating the soils with saline water. The frozen state is the primary area studied, although data during and after a phase change in the soils is also presented. The thermal properties evaluated include the thermal conductivity and thermal diffusivity, measured by means of the transient thermal probe technique, in which a metal probe is inserted into a cylindrical soil sample. This technique allows the simultaneous determination of the two thermal properties by recording the temperature response at two locations in the sample to an ideal line heat source from the probe. The experimental apparatus is described and the results are compared to several theoretical predictive methods of calculating the thermal conductivity of soils. The data from the phase change region were determined to be inconclusive and the results of the unfrozen soil were too few to find representative results. The results from frozen.state show very little effect from the salinity of the porewater. Any effects seem to be less than the accuracy of the experiment itself. The predictions from the theoretical models support this conclusion. Finally, recommended values for the thermal properties of the frozen soils are given as independent of both the temperature and porewater salinity for the ranges considered in this work.