The thermophysical properties (thermal diffusivity a, specific heat Cp and thermal conductivity l ) of Bi1.5Sb0.5Te3 were measured in the temperature range 300-700 K. The results showed that the contribution of the charge carriers to the thermal conduction is negligibly small in com- parison with the contribution of phonons at high temperatures. On the other hand, the heat conduction due to the simultaneous thermal diffusion of electrons and holes is important as well as the lattice thermal conduction. The explanation of the results was supported by using electrical conductivity measurements and X-ray diffraction.