Soil thermal properties are important to quantify the coupled flow of heat and moisture in the vadose zone. Thermal conductivity (λ), thermal diffusivity (α), thermal resistivity (r), and volumetric specific heat (C) were determined for sand irrigated with lagoon treated wastewater for 14, 8 and 0 years. In addition, thermal properties of three different desert soils (sand, loam and clay) were also determined by wetting them with tapwater and wastewater collected from the holding pond, separately. The soil water retention curves were obtained using pressure plate apparatus at 0, -0.3, -1, -3,-5, -10, and -15 bar suctions and soil thermal properties were determined at each applied suction using KD2 pro (Decagon Devices, Inc.).  Higher values of λ and lower r were obtained from sand than loam and clay for cores treated with tapwater and wastewater. Lower λ, C, α, and higher r was observed in the soil cores treated with treated wastewater than normal tapwater. Therefore, continuous application of treated wastewater can reduce heat conductance, evaporation of soil moisture but the growth and development of native vegetation as well.