The real-time thermal expansion behavior of intercalated graphite (IG) flake was studied on a hot-plate of 300°C using high-speed digital camera. A thermomechanical analyzer was utilized to investigate the onset temperature, rate and ratio of thermal expansion. The microstructures of the graphite flakes, before and after the expansion, were observed using a scanning electron microscope (SEM). The results show that the expanded graphite flake can be applied for providing electrical conductivity in polymer nanocomposite systems using a nanoplatelet inforcement concept.