Picosecond transient absorption is used to measure the thermal decay time of a mixture of higher-order fullerenes suspended in chloroform, toluene, and carbon disulfide. The relaxation time is ≈ 40 ps, which translates into a small effective interface conductance, G ≈ 14 MW m(-2) K-1. Molecular dynamics simulations of a fullerene molecule suspended in octane agree with experiment (G ≈ 10 MW m(-2) K-1) and support the conclusion that the 40 ps decay time results from the relaxation of vibrational energy and not the relaxation of electronic excitations. © 2005 Elsevier B.V. All rights reserved.