Subsurface thermal conductivity, thermal gradient, and heat flow are significant parameters when determining the feasibility of utilizing a geologic unit to generate industrial geothermal power. Cores from 18 wells of the subsurface Jurassic Smackover Formation in southwest Arkansas were analyzed at the Arkansas Geological Survey, where thermal conductivity, thermal gradient, and heat-flow values were estimated. Thermal conductivity of several samples was obtained using a KD2 Pro Thermal Analyzer at room temperature. Thermal gradients were estimated from Smackover Formation borehole temperatures, and heat-flow values were calculated from thermal conductivity and thermal gradient values. Average thermal conductivity values for the Smackover Formation are greatest in northeastern Lafayette County at 2.57 W/m·K, followed by southern Columbia and western Calhoun Counties at 2.47 W/m·K each. Northwestern Columbia and northeastern Lafayette Counties exhibit the highest thermal gradient and heat flow, with values averaging 3.51 °C/100 m and 72.3 mW/m², respectively. Interpretation of these parameters confirms that this area exhibits the highest geothermal potential for the Smackover Formation in southwest Arkansas. Investigations further characterizing the Smackover Formation, including in situ thermal properties and borehole temperature measurements, are recommended for future geothermal feasibility studies.