Carbonaceous materials have the ability to withstand elevated temperatures and structural characteristics that often exhibit changes, especially at graphitization temperatures. Stacked-cup carbon nanofibers (GSI Creos Corp., 24PS-AR50) were heat treated at ca. 3000 °C for 10 minutes in a high-purity argon stream using a graphite-resistance furnace. The heat treatment has induced a nanoscale structural change resulting in a composite texture, i.e. multi-graphene sheets rolled into concentric cylinders sheathe the stacking morphology of truncated conical graphene layers. The edge sites of graphitic layers of stacked-cup carbon nanofibers are considered to stabilize through the structural change when releasing hydrogen at elevated temperature.