C60F36 has been known to have five low-energy isomers though only three have been isolated. In order to clarify the situation, the entropy contributions are evaluated for the first time. The PM3-based thermodynamic calculations show negligible populations of the two not-observed isomers. A new, improved inter-isomeric energetics is deduced that reproduces the available observed concentration ratios. (C) 2003 Elsevier Science B.V. All rights reserved.