The thermal desorption of C6 H6 from two astrophysically relevant surfaces has been studied using temperature programmed desorption. Desorption from an amorphous SiO2 substrate was used as a mimic for bare interstellar grains, while multilayer films of amorphous solid water (ASW) were used to study the adsorption of C6 H6 on grains surrounded by H2 O dominated icy mantles. Kinetic parameters were obtained through a combination of kinetic modeling, leading edge analysis, and by considering a distribution of binding sites on the substrate. The latter is shown to have a significant impact on the desorption of small exposures of C6 H6 from the amorphous SiO2 substrate. In the case of adsorption on ASW, dewetting behavior and fractional order desorption at low coverage strongly suggest the formation of islands of C6 H6 on the H2 O surface. The astrophysical implications of these observations are briefly outlined. © 2009 American Institute of Physics.