A method of simultaneous measurement of the thermal conductivity and absorption coefficient of radiation by arbitrary heating is proposed for semi-transparent liquids and non-scattering of radiation. These properties were determined by a numerical analysis of the combined transfer of conduction and radiation in the specimen system on the basis of the measured data of the temperature changes with time. This method was applied to some kinds of liquid. The determined values of both properties agree with the available data obtained separately by using the existing methods.