Ab initio density-functional-theory has been used to investigate transfer doping between C60 monolayers and the hydrogenated (100) diamond surface. An electron transfer from diamond to C60 is predicted for a C60 coverage of around one monolayer, and the possibility of electron transfer is expected to increase for higher coverages, leading to an accumulation of holes at the diamond surface. It has been found that the greater electron affinity of fluorinated C60 is likely to enhance the effect. Results are reported on the structural and electronic properties of isolated C60 and C60F36 molecules, solid C60, and a monolayer of each material adjacent to the (100)-(2 × 1):H diamond surface.