A thermal conductivity measurement technique has been developed based on a novel design employing an ultrafine (0.02 cm dia) “traversing” thermocouple. This technique features the rapid determination of thermal conductivity as a function of temperature for specimens operating in the range from 300 up to 1200 K. In contrast to conventional “comparative” methods of thermal conductivity measurement, the present approach requires only one equilibrium condition, viz., the condition in which the specimen is maintained between the two temperature extremes of interest. The traversing-thermocouple measurement technique also permits the accommodation of a wide range of specimen sizes (e.g., 0.25 to 1.3 cm in diameter and 0.7 to 3.0 cm in length) and measurements accurate to within 5 to 7 percent. Although initially developed for use with semiconductors, the measurement technique is equally well suited to semimetals, metals, and insulators.