This work presents a method to measure the thermal conductivity and heat capacity of electrically conducting small-volume liquid samples using the 3ω technique. A mathematical model of heat transfer is derived to determine the thermal properties from the 3ω signal considering the device geometry. In order to validate the model, an experimental apparatus has been designed and set up to measure the thermal properties (thermal conductivity and heat capacity) of seven different liquid samples. The results show good agreement with other literature values, demonstrating that the suggested method is effective for measuring the thermal properties of electrically conducting liquids. More importantly, the result with a sample volume of 1μl demonstrates the resolution of the thermal conductivity as precise as 0.01% which corresponds to a thermal-conductivity change of 10-4W/mK in the case of water-based solutions.