The temperature coefficient of resistance has been obtained for the high pressure phases of silicon, germanium,and several III–V and II–VI compounds having the zinc-blende or wurtzite structure. The high pressurephases of all zinc-blende compounds were metallic. The high pressure phase of CdS is a semiconductor.Data were also obtained on CdSe at room temperature and as a function of temperature. The transitionfound optically is also obtained electrically. The resistance-pressure curve for the high pressure phase hasconsiderable structure. It is metallic.An upper limit for the transition pressures of germanium and GaSb at liquid nitrogen temperature wasestablished.