A quite different situation is observed for the phase transition of rhombohedral phosphorus to simple cubic allotrope. According to Kikegawa et al. , the pressure of this transition does not depend on temperature (at least up to 1100 K) and makes 10.3 GPa. However, in our experiments (T-scans at 8.9 and 9.4 GPa, and p-scan at 700 K; see Fig. ) we observed a significant dependence of the transition pressure on temperature, and the slope of this phase boundary was estimated as -420(70) K/GPa, which allowed us to located the rhombohedral-liquid 2-simple cubic triple point at about 8.3 GPa and 1490 K.