Lithium intercalation into coke carbon modified with mesophase-pitch and heat-treated at 800, 1000, and 3000 degreesC was observed using solid-state Li-7-nuclear magnetic resonance (Li-7-NMR) spectroscopy. It was found that the fully Lithiated state charged to 0 V in the modified coke heat-treated at 3000 degreesC showed a peak at about 45 ppm; on the other hand, two peaks appeared at about 45 and 16-17 ppm in the modified coke heat-treated below 1000 degreesC. The peak appearing at 45 ppm indicated that Li-GIC is present in the first stage, and the peak at about 16-17 ppm indicated that the lithium stored in the modified part has an ionic character greater than in the coke part and is not a lithium cluster. The lithiated states charged to 0.1 and 0.2 V and discharged to 0.1, 0.2 and 1.5 V from the charged state (0 V) are also described.