AbstractThe density as a function of temperature was determined for liquid iridium (Ir) and rhenium (Re) by means of shadow imaging in ohmic pulse-heating experiments. In addition to regular experiments at$0.23\,\text {MPa}$0.23MPa, high-pressure experiments at static pressures between$0.18\,\text {GPa}$0.18GPato$0.30\,\text {GPa}$0.30GPawere performed to increase the metals’ boiling point and thus determine density data at temperatures far exceeding the boiling temperature at atmospheric pressure. By this means, the experimentally accessible liquid range could be extended by roughly$2000\,\text {K}$2000K(Ir) and$6000\,\text {K}$6000K(Re) compared to data reported in the literature. In a second step, the experimental data were used to estimate critical temperature, critical density, and the complete phase diagram in the density–temperature plane. A comprehensive comparison with literature data was conducted.