We have measured the thermal conductivity of bis- tetramethyltetraselenafulvalene perchlorate [(TMTSF)2ClO4] in the temperature range from 300 to 6 K and in magnetic fields to 8 T in the low-temperature regime. Due to the small thermal conductance of these samples as compared to residual gases or radiation we have employed a technique which measures both the heat flow into the sample at the hot end and heat flow out of the sample at the cold end, as well as the temperature drop across the sample. We find that the thermal conductivity is monotomically increasing with decreasing temperature from 100 to 12 K as for conventional solids but in contrast to the previously published results of Djurek and co-workers. Below the anion ordering temperature at 24 K the thermal conductivity increases at a faster rate due to reduced scattering. There is a slight reduction of the thermal conductivity at low temperatures in a magnetic field of 8 T. © 1986 The American Physical Society.