We have measured the effect of pressure (0 to 17) kbar) on the resistivity and the thermopower of HfTe/sub 5/ and ZrTe/sub 5/ as a function of temperature. Pressure affects these two materials in different ways. The resistance shows a greater effect than the thermopower. There is a larger effect in HfTe/sub 5/ than in ZrTe/sub 5/. Possible explanations in terms of a Fermi surface instability and a semi-metal are given
