Low energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SRPES) were used to study the synthesis process and detailed electronic structures of graphene produced by thermal decomposition of 6H-SiC (0 0 0 (1) over bar) in ultrahigh vacuum (UHV). The LEED results showed that as annealing temperature increased, different reconstructions of 6H-SiC (0 0 0 (1) over bar) appeared and the anisotropic graphene layers were produced finally. The results of C 1s core levels indicated that the component, which was assigned to graphene emerged and the interface interaction between graphene and the substrate was weak. The existence of Si clusters was confirmed by Si 2p core levels and perhaps these clusters led to rough epitaxial graphene surface. The results of valence band spectra showed that at high annealing temperature both of sigma and pi bonds existed in the grown graphene layers. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.