We investigate the interface between a C60 fullerite film, C60F36, and diamond (100) by using core-level photoemission spectroscopy, cyclic voltammetry (CV), and high-resolution electron energy loss spectroscopy (HREELS). We show that C60 can be covalently bonded to reconstructed C(100)-2×1 and that the bonded interface is sufficiently robust to exhibit characteristic C60 redox peaks in solution. The bare diamond surface can be passivated against oxidation and hydrogenation by covalently bound C60. However, C60F36 is not as stable as C60 and desorbs below 300 °C (the latter species being stable up to 500 °C on the diamond surface). Neither C60 fullerite nor C60F36 form reactive interfaces on the hydrogenated surface—they both desorb below 300 °C. The surface transfer doping process of hydrogenated diamond by C60F36 is the most evident one among all the adsorbate systems studied (with a coverage-dependent band bending induced by C60F36).