The reaction of acetone with Si(111) surface between 750 and 900 degreesC has been investigated by reflection high-energy electron diffraction (RHEED), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). From RHEED observation, 3C-SiC spots were observed, which confirmed the epitaxial growth of 3C-SiC, and the twinning streaks appeared clearly by increasing the surface temperature. In the SEM images, the surfaces were covered with SiC islands. The average size of the SiC islands depends on the surface temperature in the measuring range. The shape of the SiC islands was not so coherent with the Si(111) substrate. Depressions and cavities patchily formed on the surfaces. Their three-dimensional structures were observed by cleaving the sample. In XPS measurements, for temperatures above 750 degreesC, SiC formation was observed. The layer thickness and composition ratio of silicone carbide (SiCx) were dependent on the surface temperature. In addition to this reaction, oxygen adsorption also occurred, the oxygen being partly bound in a silicon oxycarbide compound. Surface annealing removed the oxygen and the oxycarbide by desorption, probably of SiO, CO, and CO2, and a decrease in the SiC layer thickness took place.