We have constructed a potential energy function to model the self-assembly of rigid C-60-terminated thiolates on Au(1 1 1). This potential was used to carry out Monte Carlo simulations over a range of temperatures and surface coverage. We find the intermolecular attraction between the C-60 moieties leads to facile self-assembly. At low coverage, the molecules bind in a lying down phase; at higher coverage both lying down and standing up molecules coexist. The strong interaction between C-60 and the metal hinders the formation of highly ordered domains. (C) 2009 Elsevier B. V. All rights reserved.