Melting of phosphorus in the 2-8 GPa pressure range was studied in situ by electrical resistivity measurements in a toroid-type high-pressure apparatus with a specially designed high-temperature cell . The cell was pressure-calibrated using room-temperature phase transitions in Bi (2.55 and 7.7 GPa), PbSe (4.2 GPa), and PbTe (5.2 GPa). The temperature calibration under pressure was performed using well-established melting points of silicon, sodium and caesium chlorides, platinum and Ni-Mn-C ternary eutectic. A sample was placed directly into a graphite heater, and electrical resistivity of the cell was measured at different pressures upon stepwise heating up to the melting using the method described earlier . The onset of melting was detected in situ by an apparent drop in electrical resistance of the cell due to appearance of the conducting polymeric liquid phosphorus. In a special set of experiments it was found that phosphorus does not react with graphite and graphite-like hexagonal boron nitride (hBN) over the whole pressure -temperature range under study.