Steady-state sublimation vapour pressures of anhydrous ferric chloride have been measured by the continuous gravimetric Knudsen-effusion method from T = 383.9 K to 445.2 K. Based on a correlation of Delta H-g(cr)degrees(m)(298.15 K) and Delta S-g(cr)degrees(m)(298.15 K), a recommended p(7) equation has been obtained for FeCl3(cr): lg(p/Pa) = 1.895 . lg(T/K) - 3.047 . 10(-3)(T/K) - 3.672 . 10(-7)(T/K)(2) - 7.321 . 10(3)(K/T) + 14.017. Condensation coefficients and their temperature dependence have been derived from the effusion measurements. (c) 2006 Elsevier Ltd. All rights reserved.