We have investigated the thermal stability and the chemical reactions of C 6 0 thin films on Si(111)7 7 surfaces by the combined measurements of the high-resolution electron-energy-loss spectroscopy (HREELS) and the scanning tunneling microscopy (STM), HREELS-STM. After healing the Si up to 400°C, the molecules did not align perfectly but made local arrangements. The energy shifts of the inelastic electrons indicate that the electrons in the Si dangling bond transfer to the C 6 0 molecules. The value of the charge transfer is estimated to be 1±1 electron(s). After heating the Si up to 800°C, the smooth C 6 0 monolayer film aggregates and forms islands. The nearest neighbouring distance between the C 6 0 molecules is shortened from 10 to 9.3 . The intensity of the 92 and 101 meV peaks drastically increase. These results indicate the formation of a covalent band between the C 6 0 molecules. After heating the Si up to 1100°C, an SiC film grows.