The temperature dependence of the liquid-drop fission barrier is consi
dered, the critical temperature for the liquid-gas phase transition in
nuclear matter being a parameter. Experimental and calculated data on
the fission probability are compared for highly excited Os-188. It is
concluded that the critical temperature for the nuclear liquid-gas ph
ase transition is higher than 10 MeV. This must be taken into account
in interpreting the caloric curve in nuclear multifragmentation.