The Knudsen effusion-mass loss method was used to determine the saturated vapor pressure and molar enthalpy of sublimation for C60F18, fluorofullerene. The average molar mass of the effusing vapor was checked by an independent torsion effusion-mass loss experiment. The vapor pressure against temperature dependence is described by the equation ln(p/Pa) = -(23739 +/- 1234) (.) (K/T) + (33.23 +/- 1.97) in the temperature range (591 to 671) K. The anomalously high value of the sublimation enthalpy of C60F18 {Delta(sub)H(m)(o) (627 K) = (197 +/- 10) kJ (.) mol(-1)} compared with the values found for the parent fullerene C-60 and the other fluorofullerenes C60F48 and C60F36 so far studied, may be explained by the high polarity of the C60F18 molecule.