High pressure-high temperature equipment and procedure is described to determine the density of hydrogen fluoride as a function of pressure and temperature. An autoclave constisting of a nickel-based superalloy and a suitable pressure sensitive separator between hydrogen fluoride and the pressure transmitting fluid is used. Eleven isochors between 0.210 and 0.824 g cm(-3) at temperatures between 473 and 973 K and at pressures between 20 and 200 MPa have been determined. Previous literature data extend to 30 MPa and 573 K. Polynomials with six terms are used to represent nine isotherms from 573 to 973 K with a maximum average deviation of 0.1%, A table with smoothed density values is presented for the whole range of conditions. Isothermal specific volume data are reasonably well presented by Tait equations. Parameters are given.