Experiments probing the dynamics of a thermal wave in a material compressed at static high pressures are presented. The method involves launching a thermal wave in a sample compressed in an anvil cell and monitoring the temporal profile of temperature at a fixed point downstream. A pulsed laser incident on a metal foil provides the thermal wave, while fluorescence from a small ruby sphere yields the time-resolved temperature. Results from compressed NaCl show that temperature rises quickly and decays much more slowly, consistent with the expected heat flow. This temporal profile evaluated with a numerical solution of the heat-conduction equation or an analytical approximation provides values for thermal conductivity, thermal diffusivity, and heat capacity at pressures to 1.7 GPa. © 2000 American Institute of Physics.