Osmium hexafluoride is a yellow crystalline solid that melts at 33.4 °C and boils at 47.5 °C. The solid structure measured at −140 °C is orthorhombic space group Pnma. Lattice parameters are a = 9.387 Å, b = 8.543 Å, and c = 4.944 Å. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 5.09 g·cm−3.
^Paine, R. T. (1 June 1973). "Partial hydrolysis of rhenium and osmium hexafluorides. An improved synthesis and characterization of rhenium oxide tetrafluoride". Inorganic Chemistry12 (6): 1457–1458. doi:10.1021/ic50124a060.