We demonstrate the successful application of a new heating material, B-doped graphite (boron 10 wt%), to 23 GPa and 2000 °C. The heater resistance increases significantly at temperatures greater than 1200–1400 °C, similar to the diamond transition observed for a pure graphite heater. However, we find that the B-doped graphite furnace can be used at temperatures and pressures higher than that of diamond stability region, and that is stable for at least 3 h. Because this new furnace material is X-ray transparent and stable under high-pressure and high-temperature conditions, it is suitable for in situ X-ray synchrotron applications at high pressure and high temperature, including for structural refinement of hydrous silicate melt. High quality diffraction patterns of hydrous Mg-silicate melt were collected at 14.9 GPa using the B-doped diamond heater. Hence, B-doped graphite (diamond) is a promising heater material for high-pressure and high-temperature applications.