The X-ray diffraction (XRD) patterns of thermally reduced graphenes from graphene oxide at 80?800 ¡ÆC were investigated. Importantly, the reduced graphene at 600 ¡ÆC, GP₆₀₀, exhibits high-quality XRD patterns with a clean, sharp (002) peak with an interlayer distance of 3.392 ? similar to that of conventional graphene (~3.4 ?). The good reduction effect of the GP₆₀₀ at a relatively low temperature is explained by the balance of thermal energy required for cracking oxide groups and the defect formation of two-dimensional carbon networks. The GP₆₀₀ has average 8-layered structures with many wrinkles, a few-layered edge, including a monolayer and a double layer, and in-plane lattice ordering.